RE: Channels for separate Rudder and nose gear servos
If you are using a P-Mix, make sure that you have the mix set for both directions of stick travel. I don't know the 7C, but on my 9C, I have to make sure that it is 100% (or whatever the mixing ratio is) in both directions of stick movement (up vs down or right vs left). You may have it set to one side only.
Another option would be to flip the servo arm around so the center point is 180 degrees from where it is now. Don't know if the geometry of the connection to the nose wheel would be the same, but you might try it. If you can't there, you might try and do it at the rudder end. Make sure there is no binding or interference from other linkages.
Don't know if all that makes sense. If it does, I hope it helps you out.