I am building a Sopwith Pup and i am not understanding fully the pull pull setups.

I want to set up Rudder and Elevator on a Pull Pull system. so here goes the Q's

1. Where in relation to the control surface do the servos need to be located, are they to be directly centered in the Fuse?

2. If they are to be centered, How do you stagger the servos so that the pull wires do not interfere with the opposing servo? Does 1 servo need to be mounted in a higher position?

3. I can understand a regular pull pull system on the elevator using 1 control horn per side, But how does the top control horn work that ive seen people had wires hook to top of the elevator? wouldnt that cancel out the pull if the 2 wires ran from the same side of the servo arm? OR are they dummy wires for visual purposes??

Any help on these setups would be alot of help and very appreciated