I just picked up an XP last week too, had the 26m before that.
The ailerons on my XP are both slightly angled down, maybe by 1/16". This doesn't appear to effect how the model goes in any big way but next time I open up the fuselage I'll bend the torque rods to fix it.
As for the rudder... it's not unusual to have some coupling such that applying rudder causes the nose to drop, I've got the same thing on some of my models but I've never noticed it much if at all on the Sukhoi. I would expect it to occur with both left and right rudder. Moving the CG back might help, the battery needs to go at the extreme rear of the slot
A remote possibility is that the receiver/servo unit has come loose and moves when you apply rudder?.. Another more likely possibility but only if you have a mode 1 Tx (rudder and elevator on the left stick) is that you are inadvertently applying down elevator when you move the stick. If it was either of these issues you could expect to physically see the elevator move when you apply rudder.
PS.. as for trimming. Other than getting the CG well back it helps tons if you have a Tx that has an exponential function. The Sukhoi is incredibly twitchy and using lots of exponential allows the response to be softened while still having enough control authority for extreme aerobatics. Using the rate switches is also helpful with low rates set to about 60-70%