Well did a bit more research and found that the 20/200 limit is for already winged aviators. The SNA requirement for the USCG remains 20/50. I still am unable to find what the waiver standards are though (if there even are any?), so if any one has any knowledge on that subject, or could point me to someone I could get in contact with who would, it would be greatly appreciated.
As far as PRK goes, I'm a bit hesitant to get the surgery because I still am within waiver-able standards for the USAF without it. And according to my cousin who is currently a KC-10 pilot in the AF, that waiver is basically a formality. So if there was a way I could keep all my options open (USAF, USCG, USN) without having to get any eye surgery, then that is what I would like to do. My friend who is in Navy ROTC, however, did just get PRK done, and said it was the best decision he's made, so the option still lingers in the back of my mind.