RE: superstar float problem
The CG MUST be aft of the steps. If it's not, you'll have no end of problems on takeoff. I have a Superstar with Great Planes 40 size ARF floats, and a Tower 46, and I have been through exactly what you are experiencing now. Move the floats forward until the CG is aft of the steps by about 1/4". Until you do, takeoffs will be exciting.