Do what I did constitute a vow, and if so, can it be stopped or exited, and what should I do if I wasted hours; should I fast or are there expiations?

If the vow is intended to motivate oneself to study and not for the purpose of drawing closer to Allah, then it is a vow of obstinacy (Nathr Lajaj), for which an expiation for a broken oath (kaffarat yamin) is sufficient.