Brilliant chapter, as always. There was only one notable error (save a couple of grammatical ones that aren't worth mentioning). The spell is "Petrificus Totalus", not "Perfecto Totalus".
As for what you said about Fawkes, I can see it both ways. JKR doesn't really go into much detail when talking about Phoenixes, but I've always thought of them as representing the side of good and light. If Dumbledore is being manipulative and straying from the righteous path, then Fawkes might abandon him. However, if he's Dumbledore's familiar (as you're portraying him), then what you're saying makes perfect sense. I'm rambling. Great chapter, can't wait to read what's coming up next.
Author's response
Yeah, my beta just sent the edited chapter to me. I'll post the corrected version tomorrow. Just me being too eager to post. Look for the corrected version tomorrow or Sunday. -- Jim