2000 Grand Am Power Steering Fluid leaking

Might as well try it, but it probably wont work because the leak is big enough for you to have run out. It's probably leaking from a connection in the rear of the pump because of when it leaks. A cracked pump would be $60 give or take, a hose might be more because it would have to come from a dealer. Probably 250(max) for the job at a shop. But if that stuff works, ripper. And don't worry about damage cause you already did that by running low. The only consideration is if that stuff could hurt you rack and pinion.

I've taking it in and I'm waiting for the results, how would I know if I damaged the rack an pinion? Would the steering wheel be tough to turn?

You wouldn't most likely don't even worry. I just said the stop leak additive might