Hey Skip, glad to see you here! As I said, this is the hot spot for multi's. Great guys, and always available to give advise. More than happy to 'go the extra mile' to get your issues resolved. And, there are a lot of issues, this is all 'black magic', ( AI ), after all.
4s will give you the ability to turn large props at better efficiency than 3s and a smaller prop. There are always trade-off's. A large prop gives you lighter disc loading, making it more responsive, which the areobatic guys love. However, it can also cause the flight controller to overshoot causing a wobble, which us video guys dread.
So, to start with, a smaller prop would probably be best. Get the feel for it, then once you are familiar with it, try a larger prop and see how she reacts, whether it meets your tastes or not.
On batterys, I wouldn't hesitate to go with 4s and 8" props, it will give you better efficiency and flight times. Another side effect is the added weight can be a benefit, offering better stability.
The aerobatic guys want their ships to be as lite as possible and fly on the edge of control. Us video guys want as stable as possible.
So, you see, the trick here is to decide what you expect to do with your ship and design it for that purpose.
Really glad to see you doing your homework. Who would have ever thought all that harping your parents gave you about homework was really right after all?