I think the admswelding chap has got it right on. I've welded some stress cracks on earth movers and dozers, but never had the luxury of an air-arc. I like the old Lincoln 200 and 300 amp welders, they have a real nice arc. Personally I don't think I'd fish plate it unless I had to. It's probably the most important weld on your E, just get a pro to do it.
For the beginner, a mig welder is nice, much easier to learn with than a stick, and good for bodywork. For under $1k maybe one of the 220V ones, that you can carry, also buy your own tank with mig gas. Get a name brand, the blue or red one, I think there is one other that's good also. Be sure to ask the guys on 'Shop Floor Talk' forum, in the welding section. Phil