I will always recommend to Road riders that they follow the rules for bikes, whenever they are anatomically compatible. If you don’t ride on roads, it’s less of an issue.
Hmm, good idea! Not guaranteed to work every time, but worth a try. 
Even if you’re on a bike path that’s separated from the road, it’s important to be very aware at any crossings of it.
Then, in relation to the question of an “ultimate 36” commuter" I would recommend starting with a basic one (or just a plain KH for starters). Get comfortable riding it. On a 36" there should be a lot less dismounts; a different quality of riding than you may have experienced before. After all of that happens, then you’ll be in a better place to decide what you really need for your ultimate commuting machine.
I don’t know if the second part is true enough to ride in “stealth mode”, but I do know the first half is. Especially around 4:00am, on a Sunday morning, it’s quite a surreal driving environment on local streets. I can understand not wanting to ride with those drivers!
Brakes: I think you said Florida? Then you shouldn’t need them at all. They would only be useful for emergency stops in high gear. And you still can’t stop as fast as you can make a turn.