Didn't go past the first page and can't see the pics cause i'm at work and the comps here don't display pics (thanks to myspace!).
What kind of car is it? Is it an escort? If you want to, you can turbo it to get some more power out of it, but don't expect to run a high boost. Another thing you can do if you have some extra loot and some free time on your hands, go to the junk yard, try and find a ranger with a 2.3L or a fox body mustang with a 2.3L 4 cyl and take it along with the trans (I don't know the specs for the tranny you have) than remove your old motor and install the 2.3. It's rated about the same HP as the one you have, but you can do a lot more with it.
Actually, is it a rear wheel drive escort, or one of the newer front wheel drive escorts? If it's rear, you can do this, otherwise, it's too much work.
Other than performance stuff, rims are nice, but don't go huge. Bigger rims will make your car accelerate slower. I would say try and stick with the stock size for rims and go no bigger than 16. Paint is always good, but only if you are gonna keep the car for a while. Audio work is great cause you can always un-install it and take it to your next car; Rims don't always work this way unless you get the same bolt pattern.
Interior, I dunno, you could probably get some racing seats, but, they'd probably look retarded. I will defend anyone's right to do what they want to their car, but at the same time, will be the first to tell you your car looks like poo.