This sounds relevant to you, though it is from 2010
Also, it looks like verizon's own coverage map views puerto rico as extended 1x coverage most everywhere populated, so it should be free of charge to text and call as said. Data will be extremely slow though, I'd upload pics after the wedding over wifi or something.
Also note how the vzw rep on the link mentioned roaming on a non partner carrier, and it looks as if there are multiple cdma carriers in puerto rico. So I'd keep data roaming off, and just try to watch who you are roaming on to be safe if possible. I'm not sure how possible that is though, when I went to canada my droid 2 global didn't tell me anything about the carrier I was on, but it also wasn't verizon's extended network.