[New and looking for a "teacher" :)]

You should watch the Tekkit with Duncan series or something, go at that pace and you will enjoy the mod more, don't try and learn everything all at once :)

[Mod select button not working]

I had this problem, don't know if yours is fixed now but how I fixed mine:

Open up the launcher and go to Options, then manually set the build to the latest or any other than the recommended which I am assuming you are using. Let that one load up, or crash, either works. After it has loaded/crashed, go back to the launcher and set it back to the recommended build. That should extract some of the mod files in a quick update and then you should be fine.

tl;dr Change your build, log-in, change your build back, log-in.

Note: I just messed around with stuff trying to solve this and this worked for me. No guarantees but if you have the same issue as me, that fixed it! ^^