That is a ton of questions. But you really need to do some thorough reading on irrigationtutorials.com . Pretty much all your questions are answered on that site. I've been working my way through that piece by piece.
I am in a similar situation as you, 3/4" copper feed from the street, I have 80 PSI static pressure, and it's a bit longer from the street, but the problem is you have 3/4" feed (like me). For velocity's sake, you don't want to go over 11 GPM, realistically with other factors like the house, don't go over 9-10 GPM per zone. The reason to keep the velocity down is damage to pipes. Therefore 3/4" pipe limitation keeps you in the 9-10GPM per zone.
If you've looked at the flow rates for the heads, make sure no zone goes over 9-10GPM, you're going to need 2 zones probably at least. not sure the motivation to make just 1 zone, a second zone is only ~20-30$ more for the valve and piping...
You have to calculate all your pressure loss from start to finish, RPZ lose more pressure than say a PVB. You shouldn't have a problem with pressure, but you'll need to consult the manufacturer's spec's about what the pressure drop is. Again, this is all laid out in irrigationtutorials.