RE: NITROMODELS REPLACEMENT PARTS REQUEST_Post Here
Will leave the other questions for Nitro.
Will say the Seniorita is a great trainer they have in stock. It is easy to convert from electric design to glow. I plan to cut an extra firewall from 1/8" ply and epoxy it on. You can get a motor mount at your hobby shop. You will probably be able to rig up the mount and cut the cowl to fit your 2 cycle engine. If you need a 4 cycle cowl, I got a fiberglass one on the 'net.
I would stay away from 3 channel. Not a big difference but you will just learn have to fly 4 channel later. In training, you turn with the ailerons and use the rudder rarely.
Tom