1- Will my wings rip apart because of my bad angle and lack of epoxy? Will they rip apart if I just fly around and don't do any loops or anything that could put a lot of pressure? The wings do look solid...

I don't think you will have any problem with this wing ripping apart. I used some fiber fabric and ca to repair a fuselage that broke in half, and the next time the fuse broke in a different spot. The fabric is very strong and joins the two halves of your wing together nicely.

2- Will the .25FX engine be enough, I've hear that the Kadet LT 25 with an OS .25FX will outrun most .40 trainers! Is this true?

I have not seen the LT 25 fly, but I think that you have an excellent engine to power your plane.

3- I'm hesitating between buying a 4 channel Futaba and 6 Channel. There is a 100$ difference, should I go ahead and buy the 6 channel for future models, or should I wait because using the flaps is for really advanced flyers and I could spare the money but if you tell me that I'm going to want to have a 6 channel for flaps pretty quickly, then I will go ahead and buy the 6 channel.

I have two four channel radios and one six channel. I started with a basic four channel and upgraded to a six as I could afford it. Your six channel radio will allow you to control the receiver that you received with your four channel radio as long as you follow a few simple guidelines. In the future, you will probably have more than one plane and will be able to use the extra flight pack.