Popierre,
Don't know if this helps but I just picked up a NIB Byron Hellcat. So of course I did a search on RCU. While perusing the manual I found a couple answers for questions you were asking. All answers are on pg 17 of the manual. CG is measured at 7 3/4" back from the nose ring face. Flaps are recommended at 40 deg. Elev 3/4" up and down. Ail 1" up and down. Rudder 1" each way from center. Weight is 22 - 24 lbs. The manual does mention that the indents are there to ease finding the CG. The manual also mentions to be sure and put the gear up when you check the CG. Also says to balance for a "slight nose down condition".

Jeff