Mike,
Don't worry about assembling an ARF, if you can follow instructions and use simple hand tools, you will have no problems. You don't have to be a master builder to put one together. What's left for you to do is really easy. I assume since you are training, you have already contacted or are flying at a club site. Surely someone at the club would be willing to help you assemble and set up your ARF, should you run into trouble. As far as engine choice, while the AX and FX series of engines develope more HP and are super engines in their own rite, don"t give up on the LA series. For the price they are a hard engine to beat. They start easily and are more than dependable. I use the .46 LA in my Avistar, it generally satrts in 1 or 2 flips of the prop. It has all the power I need for the way I like to fly. Whatever you decide, its up to you. Good luck and enjoy.

Larry