Welding Tips and Tricks

In school I learned how to weld only carbon steel. I've been welding in the field for about a year now and pretty much only weld stick and dual shield on pipe because I've never learned to weld other alloys. I decided to stay after today in the shop for a few hours and brush up on some tig. Can I pretty much use all the same methods on stainless pipe as I can carbon? I know I need to purge the pipe from the inside but don't really know how much gas flow I need to use on the inside. Can somebody please explain how to purge to me? It seems a bit confusing. And can i use just a lay wire wiggle the cup technique to get my root in like I do on carbon? I experimented with dabbing my root in today and it went in decently in some spots but definitely needs a lot of work. What amperage should I use on my root?

What size and wall thickness pipe? Basically the same techniques are used on thicknwall stainless as carbon, but thin wall is a different story.

Are you using a Sep tank and flowmeter to purge? How are you capping it off? How long are you purging?