Hi Ben,
Welcome to Canreef.
I would base my decision on using sand, from what livestock I wished to keep and research. Most stores suggest using sand, as they sell it. If I added sand, I would use a combination of fine and some a bit more larger, around 2mm or so. Ok to mix a bit of live in also, but find some decently clean live sand and not filled with crap like we used to think was good to add.
A heater set just below is a desired temp, is good for keeping the temp from dropping in a cold spell or when the house heat is set lower. I run a 200w & 125W in my 90 but only the 200 is required.