G'day

The Epoxy you have will be fine so long as you make sure everything fits before you mix any up and so long as you don't do it on a really hot day. Even then so long as you have planned what you are going to do, you should have no problems.

On the subject of modifications - if this is your first model then I would strongly suggest you simply follow the instructions. Later when you have a few models under your belt, you can start some "kit bashing"

Tail draggers are a bit tougher than trikes. But they are also slightly more difficult to get off the ground. They are far more affected by engine torque than trikes.

Two aileron setups are great too but as your model is already set for one, I'd stick to that. People often do this so they can use flaperons. They are usually more trouble than they are worth. The big advantage is that if you have a computer radio, setting up is easier and more flexible.

And for trainers I always use rubber bands if that is the default. Should you cartwheel the plane, you are less likely to do damage to the wing and fuse.

Again, once you know what you are doing, you can do all the mods you like.