Regarding pay, that will have to be answered by someone local. And most of the rest will also have a local twist to it...however, most pd's...
...depending on the size; the larger agencies will run more or less continuous exams down to the little agencies that will hold an exam a year or so ahead of an anticipated opening. Guessing the ones you mentioned fall in the middle somewhere. Larger agencies many times are in a continuous hire mode and while there might not be an opening today, there might be ten tomorrow. If for no other reason, getting a test cycle under your belt is a valid reason for going ahead. The stress level will drop significantly on the next round.
The fitness requirements will vary by agency.
The background you mentioned seems fine. Just be honest and upfront with everything. Honesty counts more than a squeaky clean background.
Degrees are the way to promotion in a growing number of agencies. For some, it is a hard requirement.
I could be wrong, but the time in service doesn't mean diddly for local agencies but I think there is some type of credit for federal agencies. There are several federal agents floating around here that will be able to answer the question with certainty.
Finally, are you fully prepared to work nights, weekends and holidays. Are you ready to be a stranger in your own home. Can you in the course of the same day, deal with a decapitation and help little kids find their way home? Are you fully prepared to kill if necessary? And the list goes on and on and on.
It's a great job and you'll have a front row seat to the greatest show on earth, but it isn't without a price of admission. Good luck!
Never be afraid to make a difference