Hi!
First question: No, But naturally they will have nearly the same lenght. It is not important that the servo arm is the same lenght as the arm at the rudder...in theory yes, but in practise with the short arms we are mostly talking about here the arm lenght is of no importance.It is vital though that you allways make the servo arm as short as possible ..this for getting the least slack out of the system.

Second: You mostly don't need any bushing material...just use the thinnest cables available from sport fishing stores. I do bush the fuselage were the cables go through..just a short peice og thin plastic tubing (1cm), not heavy stuff like nyrods.

Third: I do use cables whereever I can because of weight reduction and that no bad vibrations is transformed through them to the servos. There is also much stiffer set-up with cables.
See pictures of my GP GEE BEE R-2.
Regards!
Jan K
Sweden