Sticking my neck out with a prediction, at the eleventh hour: I think that 1) the most likely solution of any proposed is that Harry will call in the debts owed to him by some of the Wizengamot members, 2) the true culprit behind the duel, GHD attack, and possible other mind-magic will eventually be revealed but not necessarily in this chapter, and that 3) it's probably Quirrel. Note that this shouldn't be taken as one giant conjunction, just three independent predictions.