Your choice of engines is great. You are on the right track on radios, I would suggest something like a 6X, the older one with the 6 plane memory. It has high/low rates and mixing and will last a long time. There are also an number of the older 3 plane memory transmitters but hold out for the six plane model.
Do not worry about growing out of the trainer right away, you will have plenty of uses for it even just as a tune-up plane from time to time. If you wreck it you arn't ready for anything advanced anyway.
The best thing to do is find an instructor who will help you and obtain his views as they will be helpful to him also, remember it's his time also. He will not want to spend un-necessary time because you have a plane not really suited as a trainer. The rest will come with time........