Can't help you with the first two questions.
My view on #3 may vary from most people. The thing is, the boot loop can happen with no warning, and there doesn't seem to be a way to truly prevent it. So my feelings are make sure you have a good backup strategy going, then drive it like you stole it. Seriously, use the snot out of it and don't worry about prevention. Why? Let me ask you this: If it's going to happen, would you prefer it happened early under warranty, or out of warranty (because you babied it) and have to repair/replace out of pocket? I feel that if it's going to happen, I'd rather get it out of the way. It's going to suck either way, so may as well hope it happens under warranty.
I will say it doesn't seem as common on the newest batches, but there's still the occasional report of it. Just don't buy it used.
4. I would suggest an extended warranty on this phone (or any phone, really) if possible. Most plans only give you an extra year, but it's better than nothing. I know the Verizon extended warranty will cover it as long as you own the phone, with no real term limit.