I'd recommend going with a newer model, or at least the one with the 1.6L. The 2.2L gets a solid 3 mpg less according to the EPA. Also, that generation was a fairly heavy car, and IMO the 94+ is just a better car. My sister has had both, and I do the work on her cars. In her 95 celica
I EASILY got 41 mpg when I had it for a week. Although, I'd really try to stick with 96+ for OBDII and it looks like they scored higher on EPA ratings as the years went on.
As far as mods go, you can do the same thing to any vehicle. I definitely wouldn't get a car based on what mods you can do to it. Start with the best you can get and work from there.