RE: 3 or 4 channel trainer?
hammonsr,
That depends on you if you are intrested in small electric parkflyers and attempting to learn on your own there are plenty of good 3 ch planes out there that might suit your needs Or if your goal is to progress to higher performance (either glow or electric) planes getting a 4ch trainer and instructor might be a quicker and less expensive way of achieving your goal.
You need to ask yourself what type of plane do I want to be flying after I learn. That answer in part should drive your decision on type of plane.
You also have to look at this as a learning experience each type of plane can teach you something. I personally love flying my GWS tigermoth in the backyard and as far as aerobatics go I'd say it the least aerobatic out of all my planes yet I find myself grabbing that one to fly off the backdeck more and more.
If you are still unsure go visit a club they might let you have a try at a 4ch trainer then you can compare it to your areobird.