The lincoln 3200 is a nice machine that welds mild steel and stainless and a variety of pot metal alloys in either flux cored wire and mig process modes. In the mig process, sheet metal as thin as 24 gauge can be welded fairly well. The standard mig gas for mild steel is 75/25 argon/co2. Welding aluminum using the mig process requires a "spool gun" accessory and more amps that this machine produces. Lincolns spool guns start around $550, but are only made for the 230v and up machines, unfortunately.
From experience with these lower power machines, I would recommend that you be concerned about making welds that appear good but are structurally inadequate for the task due to poor penetration of the weld. A weld can appear "beautiful" and have only surface penetration. Test your welds on anthing thicker than 1/8" by applying force to see if it breaks, especially if the parts being welded are critical to (public) safety. To increase penetration on thicker metals (up to 3/8") use heat (oxy-acet, map, propane). After cleaning, heat the metal(s) to red hot, then, weld.
Do not "quench" or cool with fluid (water) welds that need to be flexible, like frame, suspension, exhaust, etc parts. Quenching is a technique of tempering alloys to (typically) acheive greater hardness. Welding or simply heating and quenching a wear or bearing surface will increase life of the surface by making it harder (and more brittle).
Here is a free online welding course that is pretty good: http://www.free-ed.net/fr02/lfc/021100/ ... p?lesNum=1 . Hope this helps.