1) If you rotate the carb, the impulse hole will be blocked, and the carb won't draw fuel because the pump won't be working. You can't rotate the carb for convenience. You have to route the throttle cable to suit the engine.

2) An 18 x 6 prop may be a a bit small. The engine will tend to rev a bit high. As far as a 3-blade prop is concerned, you want it to turn in the high 7,000's. The 16 x 10 may be a bit much. Usually, though, a 2-blade works out better because you can get one that suits the engine/airframe combination that allows you to tune the airplane to suit your flying.

3) Isn't a question.

4) Breakin needs to be done at full throttle with a lot of up/down throttle changes. Your engine is likely running erratcially because the carb's blocking the impulse hole and it's not tuned right. You need to return the carb to its original position, richen the high and low speed needles a bit and go from there.

5) The spark plug gap should be 0.028"--0.030".

With the pump operating properly, the 1/8" i.d. tubing is OK. Larger won't hurt. Use a small clamp to hold the fuel line onto the fuel intake of the carb.