dumbledore walks through other people's wards like they're water. Quirrel pretends that simply sneezing is enough for him to dispell an incomming hex at one point. hacking into the hogwarts wards might be possible if one of these were to take their time and nobody was upgrading the wards.

MoR Azkaban prohibits pheonix-travel OUT, just not in. I think that anti-phoenix wards are probably one of the more difficult ones to cast, and not all wizards think that way even in MoR. but any dark wizard that thinks to have them cast can probably get them cast.