As for welding, it's not too hard to learn to make strong welds. Beautiful welds are another matter.
Seriously though, you can do just about any welding you need with a cheap stick welder for under $100 plus rods. I learned to weld doing a few smaller projects: a recumbent lowracer bicycle and a tadpole tricycle with electric assist. I got the plans for these from Atomic Zombie Extreme Machines at www.atomiczombie.com
. They have a welding basics tutorial there that is quite good. There is also a wonderful forum that rivals this one, but focused on bike building. There are numerous threads on welding.
The knowledge I gained from the Atomic Zombie forum and the skills I learned from bike building gave me the confidence I needed to even contemplate a skoolie conversion.