interesting where is your batt and receiver up front i hope, on the second ques our plane flies marvelously with out any extra weight
on the other hand when we first tried our plane with a 46tt we had to add +- 60g but that was all . we do use a big batt 1600mah so some extra there also allu spinner. it also flew well but extra power was for sure needed. hope you can fix the cg thing all that is most important is that you don't fly it tail heavy foresure recipe for crash.