Just a few thoughts, like the guys mentioned, a 175 is a good choice. Don´t know about the 110 volt though. If your looking to weld thicker material, it will probably require a pretty large fuse. My 220 volt, occasioanally, pops a 15 AMP fuse. I made a seriously thick/long extension cord to go looking for the clothes drier plug (often 220), when I´m at a buddies house.
a 175 or a 225 amp is just about all I can load in the XJ by myself and then Ím flirting with a hernia.´ Something to be said for portabilility. I´ve got a 10 AMP generator, that with the middle heat range, welds just fine. I´ve paid for the welder many times over, welding tractors and farm machinery at remote locations.
I forget the wire sizes in inches, but the 0.8 mm is standard, the 0.6 mm is easier to learn on and better for spot welds and thin material. The .06 also requires less AMPs to get a good burn, just requires a little more time and maybe a second pass (no big deal). I´ve go two pistols for mine, one for fine tip and one for standard, the smaller tip with the slightly cone end, is easier to learn on. You can more often see the point of attack, much of wire welding is by feel. A hands free mask, with a photo cell controlled filter, makes life much easier. Be careful of reflected light, I´ve sindged my eyeballs on numerous occasions. A can of anti-splatter spray, tip spray is a must, as is an assortment of tips. Straight C02 works just fine for most sheet metal and mild steel ( a lot cheaper than the Argon mixes). 18% Argon will help make the tips last a bit longer. Good thing about wire welding, is you can wet (lightly, I use a pump sprayer) your material while welding, reduces sheet metal warp and some temper problems.
I learned on acetylin, changed to rod, learned heli arch, then got into wire welding. I´m a convert, makes welding much easier.
A 3/16-1/4" hole in the top peice of sheet metal ( with an overlapping joint), a little talent and practice, makes a spot weld as good as anybodies.