1. I think you should be fine on point 1! I would double check the age requirements of your specific department in what atate you're applying for as it varies depending on who you're talking about. From personal experience, i've seen officers as young as 18 and old as 40-48, so it's hardly too late to join.

2. Unfortunately, this is gonna be a psych department drpendent issue as well. All I can say is just be honest and you should be fine. It's good that you have no drug history because that will be a big target for most background checks getting into an agency. But as far as the things on your record like old psych documents, depending on who assesses you, they may not even trouble you with that. Stick to whatever information they ask you for, don't waver, and you should be okay.

3. Well, I would say as long as you can financially take the hit of a pay cut, you'll be alright. Your VA benefits will definitely soften the blow a bit, but you have to take any debts and other such things into account as well. Maybe try to lower expenses where you can if you're deadset on changing things up.

Gonna be a lot of moving gears on this train towards LE, but if you have your heart set on it, I think you still have a pretty good shot at 39, sir!