That is an early 02. In addition to the items listed in the link below, look for a cracked radiator and keep in mind the black paint on the coolant reservoir above the turbo sometimes tended to flake off and enter the coolant stream. The link is here:
How to Buy a Used WRX or STI
and another opinion is here:
Complete USED WRX Buying Checklist
Either link will work.
The timing belt is imperative.