Mig welder questions

if you buy a flux core you can weld the floor pans but the thinner sheet metal [like quarters] will be almost impossible. you will burn through very easy on the thinner metal. I have a very old lincoln that I bought in 1992 at Home depot [lincoln 100 ?]. Then I went back to home depot to buy the gas adapter kit they sold for it. It works good. The flux core is run on "straight polarity" That means that you are actually holding the ground in your hand when welding. reverse polarity [most all of the gas/mig welders] you are holding the positive lead in your hand. Also when welding thin auto body sheet metal it helps to have the wire speed set up a little bit faster than normal. this has a cooling affect and helps with warpage and burn through just a little. I also have an ancient Montgomery-Ward "Buzz-Box" [an AC stick welder] that i can actually weld some sheet metal with using 3/32 6013 rod but it takes alot of patience. {a good workout for your curse-word vocabulary}. I would think that the Hobart 140 would be a good deal from the tractor supply. The click adjustment is not that big of a deal breaker in my opinion. Body shops tend to use 220 volt Millers. More voltage makes a faster weld and faster is better [maybe less warpage?] but more money right? Us hobby guys can get by with the 110 volt machines.