1) you do not "need" a regulator, but it is handy to have one in case park pressure is too high. I rarely have encountered that. I did put a quick connect with a pressure gauge on my city water inlet and I carry a couple of the cheapo regulators. Other have more elaborate set-ups.
2) I carry a separate black hose for hooking up to my black tank spray. You do not "need" to be hooked to non-potable water, but ok if it is available. There is an air break in the spray system to prevent back flow to a potable system. No pressure regulator needed here, higher pressure is better. Just make sure you black tank drain is open when you do it.
3) water pump burping means you are losing pressure somewhere. Could be a leak in the system, could be the check valve in the water pump itself. Most likely is the cheap check valve in the city water connection. I replaced mine with a manual valve.
4) to keep the jack from sinking into the ground/pavement and also so they do not have to crank the jack as much.
5) Sure, why not. Some people routinely turn the water pump off when they leave - no a bad idea.
6) What isn't bad for you? I use it all the time, just don't put any in the fresh tank (drain it) and flush the system really good in the spring. Don't put it into any water filters. Put some in the drains and the gray and black tanks.
7) Get yourself a battery disconnect switch. There are to many parasitic loads to eliminate all of them. Just turn everything off and disconnect the battery. Even then a wet cell battery will have an internal discharge rate of 6 to 10% per month, so a BAttery Tender is a good idea. Good info here
the 12 Volt Side of LifeOn edit - Ka Ron was quicker than me, but we agree!