RE: Fuel Tank on CG
Yes, for most glow engine you will need some sort of pump. O.S. Engines makes a few 4 strokes with built in pumps and ALL YS engines are either pressure or pumped. All gas engines have a built in pump.
Placing the tank on CG has one major benefit. The CG of the airplane does not change during flight so you will not have to change your trim settings during the flight