yea, everything is is US Dollars. Our last trip we were there for 4 days/5 nights and spent most of the time between the beach and pool relaxing. The lazy river is great, get on a tube and just float around for an hour or so.
I dont remember seeing anywhere to rent stuff at the Atlantis, but maybe in town. You can rent jet ski's at the beach at the Atlantis, they have the banana boats and para-sailing from there also. I wouldnt want to drive there tho. They drive on the left there. I was told that for real shopping deals, you need to get away from the main street on Nassau, where the cruise ships are. We never did tho. We were just there this summer, my daughter was 6 so she was only interested in playing in the sand and the pool. She made some little kid friends there and played all day.
Dont know about this time of year, but suncreeen is your friend in July.