Hey man. I'm in the same boat as you... Got out of R/C about 15 years ago, and when I got back into it, it was a whole new world.
I'm a Nitro guy, so I haven't had to get up to speed on the brushless/lipo stuff yet, but I can say that I've been doing a LOT of reading on this forum (and several others) to get educated.
All I can suggest is use the "search" function a lot, and google your heart out. That's what I've done, and I've got a decent handle on things. Plus, post your noob questions here, and the guys that check this area are really great at getting back to others with good info.
Good luck!