Using Linux really isn't that hard. I've used it off and on for the past few years, but really no heavy use, and it isn't that hard to learn.
Basically you have to learn how to use the terminal a little, for sudo or gksudo, which basically give you root (admin) privileges needed for some stuff. Installing most applications is pretty much "sudo apt-get install programname" in terminal. Start off with Debian or Ubuntu, I recommend Debian, and you should be fine. It's pretty damn user friendly, you'd be surprised.
STOP! Before you ask questions... READ the first post! RTFFP = Read The F*cking First Post
Yes, A 3.55 "jb" (cfw) is available, no >3.55 "jb" or cfw yet.
Yes, A 3.55 downgrade is available. But not to lower than stock firmware! (What it came with)
No >3.55 downgrade is out there yet.