I had one SE, and the other two were just the base S. There were different motors, up until 04, but ford decided to run the same 2.0L Duratec in all them now except for the "sport" ST model, which has a 2.3L duratec. They've got about 155hp, 135ish tq I think.
Yes everything SVT is a direct swap, you can even buy the complete SVT suspension kit for $250 NEW, including struts, shocks and springs online, because its a very popular upgrade.
Good luck man, like I said, I drove mine hard and never had a problem, and my first one I sold to a friend, who still has it 2 years later, and its got around 115k on it and he drives it harder than I ever did, which I lecture him about tearing up my baby, lol.
Any other questions let me know.