Since I'm new to corvette's, where are safe locations for using a floor jack to raise the vehicle? I know where the ones are for changing a tire but are there others? I don't want to cause undue body stress or create cracks since I don't know what all is metal and what is fiberglass.

I don't want to cause undue body stress or create cracks since I don't know what all is metal and what is fiberglass.

immediately in front of the rear wheel and on the frame rail behind front wheel where it kicks in.
Also in center of front X member if your floor jack is low enough and off center of diff housing if you can clear the exhaust.

FWIW;
the C4 has a very strong frame; so long as you are jacking on the frame you should not stress anything.
I can jack both wheels on one side of the car off the ground ( with targa in ) just using the rear jack point and still open the doors, no probs.