affect of front wheel on flying and servo
 

Yes, Pappygt, your engine should have some downthrust built in. 10 degrees sounds like a bit much, usually 5 to 7 degrees on most trainers. You should also see some right thrust built in, maybe about 3 to 5 degrees.
As to the nose gear question; yes a nose gear can severly abuse the rudder servo, especially on a hard landing or on a rough field. You should have very little movement on the nose gear, use the innermost hole at the servo and the outermost hole on the tiller arm at the nose gear. You only need about 5 or 10 degrees of nose wheel movement. Set us as stated here also minimizes the forces transmitted back to the servo from the nose gear on hard landing. A tail dragger is easier on the rudder servo but; if stiffly tied into the rudder it can be hard on rudder hinges. If you go with a tail dragger, look for a tail wheel assembly that is spring loaded to the rudder, not directly tied to it.