Firehawk153,
You're probably not going to like what I'm going to say, but either way you go you're asking for trouble. Even though the Alpha trainer is designed to be "easy" to fly, you're still going to need an instructor. Although it is possible to take what you learned on the Aerobird and make a successful flight on the trainer, the odds are pretty slim against it happening.

I don't have any experience with the Park Zone Mustang, but I do know that all "warbird type" planes are a handful. Unless you want to spend a lot of money repairing/replacing this plane I would wait until you have some more air time under your belt.

Getting an instructor is your best be at successfully starting into full RC flying. Without an instructor your flight times will be measured in seconds with a lot of repair time afterwards. Check with the hobby shop where you are buying the trainer and see if they know of any clubs or flyers in your area, more than likely they will have instructors available to help teach you. You can also look on the AMA website for clubs; [link]http://www.modelaircraft.org[/link]. RCU also has resources for finding clubs and instructors in your area, check them out too.

Teaching you to fly is only part of what an instructor will teach. they will also teach you about how to setup your plane, spot problems in the plane, maintaining the plane, how to set it up properly, how to tune your motor, among other things too. The biggest thing that I can't stress enough is they will teach safety with the plane. While you can fly your Aerobird just about anyplace, you can't do the same thing with a glow powered airplane. You are flying an object that weights 5-10 pounds, travels 50-100 mph, and has a razor spinning on the front of at 10,000 rpm. The trainer needs to be flown at a site where it is safe to do so without endangering others.

This is a great hobby and I hope that you really succeed in getting into it. I see a lot of people try without an instructor and wind up getting frustrated and quitting the hobby.

Hope this helps.