The headmaster; the teachers; some other staff such as the gamekeeper and the caretaker; the students.

The only thing said about Hogwarts teachers is that Neville Longbottom is teaching the Herbology class. Nothing about who the Headmaster is, though. it may be McGonagall or

Flitwick but that's just guessing

Not known. (The same is true for the most of the Hogwarts teachers.)

Minerva McGonagall becomes headmistress and all the other teachers keep the same positions, except of course for the Carrows.

Charity Burbage, the Muggle Studies teacher and Severus Snape, the Potions teacher. Voldemort said that he had great respect for the teachers of Hogwarts.