Ouch, a proportional throttle is not a good idea; you don't want a linear curve. That is only good for hovering IF that. You want to put the paddles on the first hole, the one closest to the leading edge when you first try them out too make sure they are not TOO fast. Once you are comfortable with that switch them to the last holes.

Flying a heli on an airplane radio is a very bad idea because you can only adjust it mechanically. Where do you live at? I would recommend trying to find someone local who could help you out.

It is impossible to do 3D with the setup you have now, you'd be lucky to get a loop, a stall turn, and a roll in with your current configuration and they would not be very good at all. Most radios have 5 pitch curves for 3D the best have 13 and the low end have 3... You have 1 and it's mechanical. VERY hard to work with.