The grammar is the same as in Spanish: "finished" (=acabado) can be used either as an adjective or as a past participle. We use "have you finished?" in the same situations as you would use the pretérito perfecto "¿habéis acabado?" and "did you finish?" in the same situations you'd use the pretérito indefinido, "¿acabasteis?" in Spanish. We often say "are you finished [=adjective]?" but I don't know if the equivalent "¿estáis acabados?" is very good Spanish. All three forms are grammatically correct, but as Mark says, "did you finish ..." is more commonly followed by a predicate like "... the exercise" or "... on time".

Most teachers in school would actually say, is everyone finished? If you live in Texas though, you will often hear, are you all finished? But I'm so used to hearing, is everyone finished.

"Are you finished" would be the most typical way to ask; "have you finished" is a bit formal. "Did you finish" would not be quite correct, unless you were talking to one specific person.

'Did you finish' would be okay if you add 'the task on time?' But usually 'Have you finished?' is the better question.