i prefer a thin layer of dark substrate. The general rule of thumb is 10 adults per gallon, but you can go over that if you are dilligent. I prefer 20 longs but I do use 29g and 30g as well for breeding tanks. You can comfortably keep many hundreds in those sizes. Sponge filter (hydro pro line) are my favorite. You may not need a heater if your house stays in the 70's. Do some low light plants or make sure you let the tank really establish. Feed VERY lightly, I feed 2x per week about 1 pellet per 10-20 shrimp. They will graze constantly on infusoria, biofilm, microalgaes, film algaes, etc and need very little supplementation if its an established tank.