each of those is a seperate issue

Ailerons, typically with a 1 servo setup you have one aileron on the left of the servo and 1 on the right.. so when the servo moves 1 goes up and 1 goes down

    For a 2 servo setup you keep the rigging the same... on 1 servo you have the connection on the right, on the other servo you have it on the left... what this does is since the servos move together you get the same function, one goes up, one goes down

    For 4 servos on a biplane, just multiply the above by 2.

    if for some reason you've set them up with all connections on the same sides of the servos... then  you'd need to use seperate channels on your radio and connect them together or get a servo reverser.



For the elevator... like I've described it above... you can either keep both connections on the same side of each elevator servo, or hook it up as its conventient to you and use multiple channels on your radio to control each servo.