Hi Harry

A lot of your rocking may be caused by to much dihedral. If you reduce the wing span of that airplane by removing one bay from each wing tip you will have a whole new and much better flying 4 Star.
Your bouncy landings and ground looping are probably caused by the landing gear being to far forward. If you are flying off of a hard surface try placing the gear so that the wheels touch the surface 15 to 20 degrees in front of the cg with the plane level. If you are flying off of grass the angle will need to be about 25 deg. Also make sure that the wheels are pointed straight ahead or toe'd in a little. If they are toe'd out and cambered out (normal after a few hard landings) this will cause ground loops.
Yes you need a little down thrust. Add it in about a degree at a time. Better yet if you have a computer radio slave some down elevator to your throttle.
Retrim your ailerons. You don't want permanent flaps. If any thing you want them reflexed a little. Fix this before putting down thrust in the engine. Fixing the ailerons alone may correct your pitch trim with speed problem.

Denis

Denis