I used to do a lot of TIG welding when I was in the RAF, the equipment we had back then would handle a over 500 Amps using a 3/16" tungsten electrode! Had to suit up to use it, any exposed skin would get terrible arc burn, don`t ask me how I know!
I actually agree with you that TIG welding has a lot in common with gas welding in that you have the heat source in your right hand, while manually feeding the filler rod using your left. The difference is that you have a foot pedal with which to adjust the heat as you go. I would not recommend buying any TIG welder that did not come with a foot pedal, if that is what you are familiar with.
Make sure that the place you purchase from carries a good stock of ceramic shields, there is nothing worse than having all the equipment and not being able to use it because a shield has a crack in it. I remember putting in a military requisition for 6 ceramic shields, a month later we still had not received them. A couple of weeks later we took delivery of 6 new TIG welding plants, someone had got the wrong part number! It wasn`t me, honest. What worried me at the time was that I could order equipment valued at hundreds of thousands of dollars without anyone ever questioning it!
Bob