I happened to be redirected to the official FAQ at JKRowling.com and I compiled a list of the most interesting answers from her Q+A:

Tonks was in Hufflepuff, Myrtle was in Ravenclaw.

Alecto and Amycus are the two sibling Death Eaters surnamed Carrow

The Order of the Phoenix communicate using Patronuses with a method taught by Dumbledore, who invented that way of communicating. They are not hindered by physical barries and are unique to each person.
Dumbledore's Patronus is a Phoenix.

Flitwick is human with a dash of goblin ancestry (great, great, great grandfather).

The core of Hermione's is dragon heartstring.

Godric’s Hollow is a village.

Peeves isn't a ghost; he was never a living person. He is an indestructible spirit of chaos, and solid enough to unscrew chandeliers, throw walking sticks and chew gum.

On Veritaserum:
"Veritaserum works best upon the unsuspecting, the vulnerable and those insufficiently skilled (in one way or another) to protect themselves against it. Barty Crouch had been attacked before the potion was given to him and was still very groggy, otherwise he could have employed a range of measures against the Potion - he might have sealed his own throat and faked a declaration of innocence, transformed the Potion into something else before it touched his lips, or employed Occlumency against its effects. In other words, just like every other kind of magic within the books, Veritaserum is not infallible. As some wizards can prevent themselves being affected, and others cannot, it is an unfair and unreliable tool to use at a trial.
Sirius might have volunteered to take the potion had he been given the chance, but he was never offered it. Mr. Crouch senior, power mad and increasingly unjust in the way he was treating suspects, threw him into Azkaban on the (admittedly rather convincing) testimony of many eyewitnesses. The sad fact is that even if Sirius had told the truth under the influence of the Potion, Mr. Crouch could still have insisted that he was using trickery to render himself immune to it."

On magical education:
"Most children are home educated. With very young children, as you glimpsed at the wizards' camp before the Quidditch World Cup in 'Goblet of Fire', there is the constant danger that they will use magic, whether inadvertently or deliberately; they cannot be trusted to keep their true abilities hidden. Even Muggle-borns like Harry attract a certain amount of unwelcome attention at Muggle schools by re-growing their hair overnight and so on.
Everyone who shows magical ability before their eleventh birthday will automatically gain a place at Hogwarts; there is no question of not being ‘magical enough’; you are either magical or you are not. There is no obligation to take up the place, however; a family might not want their child to attend Hogwarts."

Weasleys:
Bill is two years older than Charlie, who is three years older than Percy, who is two years older than Fred and George, who are two years older than Ron, who is a year older than Ginny.

Why could Harry see the Thestrals 'Order of the Phoenix'? Shouldn't he have been able to see them much earlier, because he saw his parents/Quirrell/Cedric die?
I’ve been asked this a lot. Harry didn’t see his parents die. He was in his cot at the time (he was just over a year old) and, as I say in ‘Philosopher’s Stone’, all he saw was a flash of green light. He didn’t see Quirrell’s death, either. Harry had passed out before Quirrell died and was only told about it by Dumbledore in the last chapter.
He did, however, witness the murder of Cedric, and it is this that makes him able to see the Thestrals at last. Why couldn’t he see the Thestrals on his trip back to the train station? Well, I didn’t want to start a new mystery, which would not be resolved for a long time, at the very end of the fourth book. I decided, therefore, that until Harry is over the first shock, and really feels what death means (ie, when he fully appreciates that Cedric is gone forever and that he can never come back, which takes time, whatever age you are) he would not be able to see the Thestrals. After two months away from school during which he has dwelled endlessly on his memories of the murder and had nightmares about it, the Thestrals have taken shape and form and he can see them quite clearly."

What happens to a secret when the Secret-Keeper dies?
"I was surprised that this question won, because it is not the one that I'd have voted for… but hey, if this is what you want to know, this is what you want to know!
When a Secret-Keeper dies, their secret dies with them, or, to put it another way, the status of their secret will remain as it was at the moment of their death. Everybody in whom they confided will continue to know the hidden information, but nobody else.
Just in case you have forgotten exactly how the Fidelius Charm works, it is
"an immensely complex spell involving the magical concealment of a secret inside a single, living soul. The information is hidden inside the chosen person, or Secret-Keeper, and is henceforth impossible to find -- unless, of course, the Secret-Keeper chooses to divulge it" (Harry Potter and the Prisoner of Azkaban). In other words, a secret (eg, the location of a family in hiding, like the Potters) is enchanted so that it is protected by a single Keeper (in our example, Peter Pettigrew, a.k.a. Wormtail). Thenceforth nobody else – not even the subjects of the secret themselves – can divulge the secret. Even if one of the Potters had been captured, force fed Veritaserum or placed under the Imperius Curse, they would not have been able to give away the whereabouts of the other two. The only people who ever knew their precise location were those whom Wormtail had told directly, but none of them would have been able to pass on the information."

On The Harry Potter Lexicon:
"This is such a great site that I have been known to sneak into an internet café while out writing and check a fact rather than go into a bookshop and buy a copy of Harry Potter (which is embarrassing). A website for the dangerously obsessive; my natural home."

-J

 

lulz.

Those are pretty interesting, and it eliminates some of those "plot holes". I found some pretty good stuff in HBP too. As in Harry using Petrificus Totalus and disabling - what was it? six? - Inferi with that one spell. This means three things to me.

1. This is how Dumbledore owned all the DE's in the DoM
2. Harry's powerful enough to do it, though perhaps not on Dumbledore's scale
3. Harry is going to use this power in the next book

Then there was Dumbledore's explanation about people fearing the unknown rather than death and darkness in and of themselves. Is he referring to multiple things? Saying that Dark and Light magic are non-existent barriers created by people's fear? Is he trying to tell Harry that the actions that a person uses the spell for rather than the magic itself is bad? Telling him that perhaps dark magic can be used to his advantage?

Who knows, but I think what we find out about Dumbledore in the next book is gonna be a doosey.

 

Excellent find.

I'm glad I finally know about the Secret-Keeper thing. It has been irking me for ages.

 

Her statement on the Secret Keeper and the Fidelius Charm is one of the things that irks me.

She says: "In other words, just like every other kind of magic within the books, Veritaserum is not infallible" and then she describes the Fidelius Charm as infallible and permanent.

I'd rather prefer if all magic volatilizes a while after the caster died, like the charm on Harry on top of the tower. Perhaps with the additional twist that some kind of magic like the wards of Hogwarts 'feed' on the inhabitants. Most of the readable fanfic authors describe it that way, too.

 

It'd be fun to to entrust the infomation that two plus two equals four to a Secret Keeper, and then kill him

 

If the Secret Keeper's charm stays the same, why didn't they use Grimmauld place during HPB? Weren't they scared that Bellatrix or whoever might claim it. Then again, I might have just read too much fanfiction.

Number three is the most amusing. I can just imagine the final battle.

The Inferi approached Harry, whilst Voldemort laughed victoursly.

Harry stared at the mass of Inferi, before shouting "Screw this. Wingardium Leviosa!"

Voldemort simply stared in shock as the Inferi were flung into orbit. Dropping his wand and raising his hands, he weakly mumbled "You win"

 

Well, it'd be interesting no? I'm thinking more like

Harry could tell that these three Death Eaters were new recruits by the way they fought out of tandem. He stepped back a bit and waved his wand, chuckling as they all fell as stiff as boards to the floor.

 

I'm still not satisfied with the explanation of the fidelius. When Peter had to tell the people the secret for them to find the Potters, how could Hagrid find Harry and take him away?

Assumed he knew the secret this means he Peter had to tell him, so he would have known that Peter was the secret keeper.
Even if he had known and could just not tell Dumbledore that it was Peter and not Sirius because the spell would prevent it he would not have reacted that way in PoA when he heard from McGonagall that Sirius was secret keeper.

He would at least have tried to question why they would take the obvious choice to go around the charm...

Has somebody an explanation for this? I'm really confused...

 

I'm thinking the spell was null and void with no more secret to protect. What's the point of keeping the secret of two dead people?

 

While afrojacks' explanation is plausible, I always thought that the Fidelius, canon defined is a very powerful and obscure bit of magic, was a ward tied to a physical structure, like the house the Potters were hiding in or runestones place strategically around the property. When the house exploded, the charm expired because its physical parameters had been destroyed.

 

That too. Either way, the spell got fried, so I don't think it's really that much of a plot hole so much as something that hasn't been explained, and I happen to like Muttering's way of explaining it, as I had forgotten that the house got obliterated, hehe. Here is what interested me most though

It's not a question of being magical enough. You are either magical or you are not. That right there might throw the question of magical power out the window. What does that leave in its wake as to determine who wins? More knowledge? More willpower? That would essentially bring two important concepts back into the fold. No longer would it be simply a matter of whose more powerful to begin with. We'd get "Knowledge is power" back, and we'd get the concept of "who really wants it more" back too. There are upsides and downsides to this. All kinds of theories are given new life. Is magical power originated in the body (magical power) or is there something in a wizard's blood that taps into the magic of the earth and that the amount a wizard taps into is standard for all wizards and the only difference is how efficient you are at using it? It may seem like over analyzing, but shes been known to hide clues in her words. Ughh, headache approaches.

 

May I direct you to this essay.

It sums up my ideas about magical power much better then I can.

 

We know that the secret can be written down by the Secret-Keeper (Dumbledore as the keeper of 12 Grimmauld Place), so it stands to reason that to keep the true identity of their Keeper hidden, the Potters chose to use a written note rather than let everyone know who their Secret-Keeper was. Hagrid never necessarily had to know that Sirius was the Secret-Keeper, all he had to do was read the note.