bemyself, welcome to the hobby and to RCU.
I will see if I can help you with come of your questions.
1) Between the two engines, the differences are small. I would get the one that has the easiest access in your area. No need to purchase a engine that is not distributed in your location and no one can help you with it. The only one that I have experence with is the TTiger. They are great engines and very powerful for their size. I would go with it.

2) If there is a chance you are going to be flying helicopters then get the 6 xhps. If not then the 6 xaps. The 6X's radios have more features than the 6E or skyport. You can go to www.futbabrc.com and do a comparison of the details of each model.

3) FM and PCM, you will get a lot of arguments on which is better. With a trainer, I would not worry about PCM. The 6X's transmitter will handle both. I use PCM for safety only. If I have a glitch or problem on the ground, my engine just goes to idle. I had a plane run away once because my transmitter turned off from a loose battery. SInce then I use PCM.

I hope this helps