Exempt status has nothing whatsoever to do with working hours. There is no law anywhere that says you don't have to work if you don't want to. Both exempt and non-exempt employees MUST work the hours their employers' want them to work - the only difference is that a non-exempt employee get paid overtime if they work over 40 hours in a week (the 8 hours in a day applies in only 3 states - yours is not among the three states) whereas an exempt employee does not. However, an exempt employee also gets paid for the full work week if they work any part of the week (certain exceptions apply) whereas a non-exempt employee does not. There is NO "unspoken rule" that an exempt employee is supposed to get bonuses. They MAY get bonuses but there's no legal requirement for it.
They most certainly can require that you work late, fire you if you don't, and you will not have any grounds for a lawsuit. It is QUITE common and very, very legal for an exempt employee to work 50, 60, 70 or even more hours a week on a regular basis.

