The type of Visa you need depends on what you want to do in the USA and should be made clear at point of entry.
To get an initial TSA clearance will take time (weeks) and involve finger printing and that is a greater concern as the training establishment have to register you with TSA too.
My guess and its only a guess is that you would be better sorting the TSA stuff before you go stipulating the school you intend to use.
If on arrival you don't like the school it should then be easy to change that within the USA than starting from scratch there.
The VISA is a different matter although I have heard of pilots using a holiday VISA while training. i hold a B1/B2 C1/D
Pace