I'm pretty sure that I have asked this question before and been answered but I can't remember anyway when it comes to center of gravity of a plane, should it be slightly tail heavy? Am I correct in assuming this
No, you want it slightly nose heavy. Nose heavy means more stable flight. Tail heavy is for 3D planes where you want to do a lot of harrier movements or hovering, but is harder to fly.
All of my planes made for 3D... are slightly nose heavy... While a tail heavy plane is less stable, I'm not sure any of the pilots actually like to fly them that way... They want good control like the rest of us.