You just take the 9C out of heli mode and put it in Acro mode. complete different mix program sets. Read the 9C manual (if you lost it, you can download it, there's a link on Tower's ad for the radio)

Generally the idle hold and idle up are just heli settings. If you are properly flying the plane you vary the throttle throughout an aerobatic maneuver to maintain a constant airspeed.

Caps are generally considered WAY advanced for learning to fly fixed wing. Learning basic level flight and how to handle loss of engine are better done with a plane that has a better chance of recovering from a mistake is preferred. You may be fine as long as the prop keeps turning... but lose power and you could be in for a costly lessson.