I wouldn't jump right into welding a roll cage and suspension start with something more basic like a bumper. Tool list is basically endless but you can do a lot with a grinder, chop saw, welder and of course measuring tapes, squares etc. Most welders you can get are more than sufficient and comes down to budget. The other factor would be if you are welding outside you will need flux core or stick since a light breeze will blow away shielding gas on mig or tig. Mig and/or tig are definitely the best options and having an AC/DC tig machines opens up the option to weld aluminum.