Geez Chris, you can sure pack a lot of questions into a paragraph!



I've done this many times, and here's how I do it.

Use the higher settings for the thicker metal. Sideswipe the bead into the thinner metal as you go. Careful, or you'll burn a hole. If you do burn a hole, go to lower settings, fix the hole, then go to higher settings and continue.

If you're welding ss to mild steel, use ss wire and tri-mix gas.

Stainless MIG welding has a different "feel" but the technique is exactly the same. I find that ss seems to want more heat for the same penetration, but be careful, or you'll ruin the anti-oxident properties with too much heat.

jp