Which salt to use is one of those questions that if you asked 10 different people you would get 11 different answers. Find out what`s readily available at your LFS
and try one and see. If you do a search here you will find many Salt threads that tell you who uses what and why. There is no best salt mix out there or we would all be using it. They all have their pros and cons.
As far as the rock I think the above thread gave you a good estimate. Sumps are always a good idea as added water volume is a plus. Aragonite sand is preferred and for a FOWLR
tank any lighting will do. When you go reef you`ll need to check out some VHO
or T5HO lighting.