Going to be buying a Tib, want some help

Hi, I am going to be buying a 08 tib. I dont know much about cars, but i have always wanted a tib they look cool and the few i have driven they are great rides.

I want to know the differences in the transmissions from GT to SE, whats better for performance

Also what are some of the cheap first things i can do to it when i get it to increase performance such as cool air intake.

Any help would be great Thanks.