Wow David,
You really are at ground zero. I'm not even sure where to start.
Your project is really ambitious, not impossible, but people make a living modifying off road vehicles. It all takes time, and a pile of cash.
Well, lets start with your welding. Yeah there's lots of books and video's on YouTube but you really need someone to teach you. Gas Metal Arc, Oxy-Fuel, Tungsten Arc...doesn't matter which weld process you choose, you'll need someone to give you some practical training. You gotta get structural element right (design and fab).
My 2 cents
Tyrone