As one who has and still uses push pull on all my big models and most of the small ones, I can conscientiously give you the following advice that has always proven correct.
Number one and probably most important; use a bit of positive Ackerman.
Do not over tighten the lines, have them just barely taunt at neutral, thenon pulled line will slacken a bit as you pull off neutral.
You can have the arm length different between the servo and the surface, either way depending on whether you want more or less throw. Just make sure that, if the servo arms are the longest, you do not try to move the surfaces more than about plus or minus 90 degrees and even that will be a bit of a strain.
The servo and the surfaces do not have to be in the same plane or even on the same axis if you use good guides. I use nylon tubing to route the cables around and through obstructions with never a problem in either accuracy or ease of control. The secret is to have the guides well anchored where the lines enter them at the servo and also where they exit the fuselage at the tail as well as anywhere in between where you are changing direction. I use pull pull on both elevator and rudder as it is so much easier and more precise than push rods are, also lighter and more durable and completely free from vibration. If you are in doubt about Ackerman, Google the term, there is lots of info available.