Welcome!!
I got married at the GBP Akumal, and I LOVED it!!! So if you have any questions please don't hesitate to ask.
As for the reception by the pool... I had one. AMAZING! I would HIGHLY recommend it. I actually had my entire dinner out there, so the cost per person for that took care of the set up costs and the drink costs. I'm pretty positive that if you choose to only do drinks out by the pool, the price still includes a small set up. The DJ was the resort DJ and he was $150 an hour. I know a lot of brides are starting to bring in an outside vendor, however and he too is $150 an hour.
As for photography, I hated the resort photographer so I flew my own photographer in. For $2500 I got three full days of coverage, all the edited pictures on a disc, and amazing pictures which capture all of our special memories. I would HIGHLY recommend going that route.
Best of luck and please don't hesitate to let me know if you have any questions!