The Protege is the sedan, the 323 is the hatch...you're getting "Protege 323" from the emblem on the back of the car - don't be confused, you own a Protege and not a 323.
Escort sideskirts(like the GT sideskirts that don't go up the side of the car) will fit the Protege, however as I found out you have to drill holes in the body to mount it, and you also lose your front mud flap(actually you might be able to swap the skirts on each side so that they are backwards...I didn't even think of this when I test-fitted a set at the junkyard last weekend).
Front and rear bumpers are a different story completely...if you mean you want to use part of an Escort bumper(add on body kit) it prolly won't work, and the only way to get an Escort front bumper to fit the Protege is by cutting the hump off the top of the bumper where the grill goes. Rear bumper might be completely different from the Protege, I don't know, but Escort bumpers are ugly IMO. Get yourself a Familia front bumper, you have 2 basic styles to choose from, the one on my car(in my sig below) is off of a Familia GT-X.