I don't think there's reasonable evidence to say Binns doesn't know he's dead. I find it hard to believe he didn't find out eventually.

 

I was not arguing that there was. I was merely speculating that there is a possibility that Binns was using physical notes based on the following quote from Canon:

 

I don't think he was entering his classroom through the black board when he was alive, so this rumour is probably exagerated.

As to his notes, Pottermore shows them as physical books (for what it's worth):
http://img1.wikia.nocookie.net/__cb20120919155135/harrypotter/images/7/70/HistoryofMagic.png

If Myrtle can cause inundations and violent ghosts are plausible culprits for the destruction of the Shack, it's not impossible Binns can turn pages.

 

Can a killing curse, kill creatures like a Basillisk, Dragon or even a Nundu?

 

Unknown. The Killing Curse can definitely kill animals (spider in GoF, fox in HBP) and is stated to be unblockable. At no time is size mentioned as a barrier to the killing curse's effectiveness. Physical objects can act as a barrier to the killing curse, but not always: one of Dumbledore's statues in OotP was blasted apart by a Killing Curse, another happened to reflect it away.

Those facts would seem to imply that the Killing Curse should kill large magical animals: the Killing Curse's power is said to be absolute, and no exception for certain magical animals is provided.

However, certain animals are said to have magically resistant skin. We see the reduced effectiveness of spells against magically resistant skin in GoF against the dragons (requiring multiple handlers to subdue a dragon) and in OotP with Umbridge and Hagrid. But it's not clear if magically resistant skin would come under the category of "blocking" and therefore not have any effect on the Killing Curse.

Wizards appear to have a healthy fear of giants and other dangerous magical creatures. This would seem to imply that there isn't a relatively simple way to take them down, and the magically resistant skin would provide a canonical explanation. However, it could simply be that the Killing Curse, as powerful dark magic with many negative associations, is not even considered for use by most wizards, not even in self-defence, not even against animals.

On a final note, it's worth taking into consideration that, although in the books the Killing Curse is always represented as absolute--you can't block it, it causes death if it hits you, with no way to reduce its effect to a lesser injury--JKR has spoken of it out-of-book as being able to be reduced in effect in exceptional circumstances. This is what happened in DH, according to JKR: Voldemort not being the master of the Elder Wand, and Harry being its master, reduced the power of Voldemort's killing curse so as to allow Harry to survive it.

This can be made compatible with canon if you think about fake Moody's nose-bleed comment in GoF. The Killing Curse's effect is absolute, but only if you cast it successfully. Unsuccessfully casting the Killing Curse results in a lesser effect. So the Elder Wand working against Voldemort in DH may have downgraded his Killing Curse into the "unsuccessfully cast" category, but right on the brink: it was still enough to send Harry on his way had he not wished to return to life.

 

Actual Cannibal Taure : So no definite answer, but leaning towards no?

But the killing Curse has to have some effect on the magical creature even under that theory. How would you make a curse that is meant to kill only partially affect something? May be it would be stunned for a few hours instead? But that would be almost as advantageous as instant death, and then wizards will have no reason to fear dragons and its like. You could have it incapacitate the part it hits -- but then, a well aimed curse to the head or the heart will still finish it off. So, what can this "lesser effect" possibly be?

 

Well, the Basilisk's gaze is instant death as well, but not if it's seen through indirect means. Perhaps the killing curse would work the same way.

 

Can Protego only block magical attacks or also physical ones ( I think it can both but too much fanon has left me unsure)

 

It can block both. In DH the charm is used twice to block physical objects: once by Harry to separate Ron and Hermione; once by Hermione to separate Harry and Ron.

For completeness sake, it can also block mental attacks -- Harry used it in OotP to block legilimency. But I guess this is a kind of magical attack.

 

Can Apparition be tracked from the Ministry? I mean, you need a license to do it, and you're fined (heavily, I presume) if you Apparate without one, but how would they know who it is that does the Apparition?

 

Lupin states that it's impossible to track apparition in chapter 11 of Deathly Hallows, unless you grab hold of the disapparating person (as Yaxley did).

There does, however, appear to be an exception to the rule. At the start of Deathly Hallows, it's stated that Harry cannot be apparated out of Privet Drive because Pius Thicknesse had made it illegal. Now, given that the Order has shown complete disregard for the law on many occasions, there must have been a substantive reason for abandoning the apparition plan. Some reason the law was enforceable. This would suggest the apparition is trackable if one of the apparators has the Trace.

 

That doesn't have to impact the analysis. Harry and Dumbledore's trip was within Hogwarts term-time; the Reasonable Restriction of Underage Sorcery would not apply during that period so no one would be looking at the Trace.

 

Or you could just consider that Dumbledore is awesome, and say that explains it. Maybe Dumbledore is the anti-trace.

 

The ministry can detect that magic was cast, but not the perpetrator, according to Dumbledore in Half Blood Prince chapter 17, A Sluggish Memory (Pg 344 of my copy of the book).
The ministry might have been able to detect that apparation was done, and that Harry Potter was in the vicinity of Albus Dumbledore. Whatever monitering person/charm was observing that information probably just figured it was Dumbledore casting the magic.

 

I think there are some magical creatures the Killing Curse cannot kill, or at least not easily or by any wizard.

The best evidence for this is the Nundu. It is described as requiring 100 wizards to take down, which implies that either wizards are completely opposed to ever using the Killing Curse, or it can resist its effects to some degree.

Given that the Nundu kills many with its poisonous breath, and Mad-Eye was not seen as exceptionally evil for killing spiders with the Killing Curse (though people were still shocked, they didn't immediately jump to "OMG, he's evil!'', I think it's the former.

There must still be ways of killing magically resistant creatures like Giants given that they haven't taken over the Wizarding World. We can go with the idea that multiple Wizards must attack them at once, or with the idea that though they may resist spells, they might not resist physical results from spells quite as much. Something like a fire that is magically started, or a Goblin sword, would probably harm them with much less issue.

Edit:

More evidence for Wizards being able to effectively manage Dragons is their use in magic-- their blood has a bunch of special magical properties (Dumbledore mentions them, IIRC he discovered them?), which implies there must be a certain amount available for sale, so there must be some relatively consistent way of killing them for ingredients (like Heartstring for Wand cores.)

 

They might also just be very fast and hard to hit with a Killing Curse (especially if you want to be sure you dont hit one of the 100 other wizards trying to take it down). That would fit them being described as large leopards.

I think those are just harvested from dragons that die from natural causes, but that might be fanon.

 

Do we know how Molly was able to get money out of Harry's vault? If i remember correctly Harry got his vault key from Hagrid after the Gringotts visit in PS, and he didn't give it to anyone after that. In fact is that the only time the key is mentioned in the whole books? Can's seem to remember hearing about it any other time.

 

I have an argument that the ministry can track apparition to an extend: They have to find people who splinched themselves on a regular basis.

 

I don't remember where it was stated but I think the people that apparated where under age. So I would say that the trace that's put on all underage wands is probably how they are found.