Yes your rims would fit a 2000 GT.
Rust is the main thing you want to look at on a 97-03 body style. Rear strut tower rust under the carpet is something to look for and the rocker panel rust. Both are the most commom places to rust first. Otherwise 97-03 has different quirks and issues than the 04+ but the main problem or general repairs are the same.
They run the same engine/transmissions with the same issues, same basic suspsension setup and common things there. The Na 3800 in that GT will for sure feel slower than your GTP.
