You can't really see any fireworks from POR. You might be able to catch a few bursts from Illuminations at Epcot (I saw them from the parking lot at POFQ)...but it's certainly not a whole show and nothing worth planning in, IMO.
You can use the beach at the Poly to watch the MK fireworks show, Wishes. You do not have to be staying there to do this. I actually prefer watches Wishes from the Poly rather than inside MK because it's not as crowded and you can easily find a place to sit down! Although it will still be pretty crowded at the Poly since you're going during Holiday time.
The easiest way to get back and forth from the Poly to POR would be to take the bus for MK. Then you can either hop on the resort monorail, or take a boat to the Poly. Just reverse that to get back to POR.
If by wait you mean transportation time, I would leave POR 2 hrs before the fireworks time. That will give you plenty of leeway to catch the bus, catch the monorail or boat, and find a spot on the beach while there are still chairs available.
Note: The music for Wishes is piped in near the Poly beach, but the speakers are up near the buildings. So if you want to sit on the beach, be sure to sit up as close to the sidewalk/grass/buildings as possible so can hear the sound. The beach area directly in front of the pool is not a good spot if you want to hear the music as you're sitting somewhat far from the speakers.
