Read the owner's manual. All the info you need is in there, including shut down procedure.Never owning a car with a turbo before leaves me without a lot of knowledge on what to do.
No.Does a 13 WRX need a TT
No.or is it a good idea without much gain?
A few hundred USD from memory but it's not necessary. There should be a harness.What do they usually run price wise and is it all one unit or is there wiring harnesses or other items that need to be added, as well as what degree of difficulty is it to install?
Skip all that.