Because you're in Florida with your weather I think you could probably get away with out sealing. I use tile lab sealer on my birdbaths as I do get some freezing, although in the worst weather I take my birdbaths into the garage so there will be no issues with them. There are some sealers which ae used for driveways and interlocking bricks which are great sealers but not for birdbaths, I think they have a skull on the container, and they even smell horrible.As far as paint goes, I think it would be okay if it's a acrylic or latex paint. You could also seal over the paint. I have several painted cast concrete leaf birdbaths which I sealed with tile lab,
Cindy
Cindy

Panther, I live in northeast Florida. I have 2 concrete birdbaths outside. The first one I made probably 3+ years ago. It was my first mosaic, so I knew nothing of sealing, admix or anything else. I just grouted it with plain white grout. The second one I did last year, which I did add admix (an acrylic additive for strength) to the grout but no sealing. They both do fine all year and I have never found any dead birds or critters near my birdbaths. And I do l have A LOT of trees in my yard and in the neighbors. I just finished one for a friend and I did use TileLab to give the grout a nice finish.

I have some terra cotta trays I've made as birdbaths (some people call them butterfly trays) and I have sealed those with a concrete sealer because of the terra cotta. I also have never had any problems with them killing any birds.

Thank you both, I feel more confident about picking my materials now.