I dove with Tank-Ha in February. Good operation, fun DM. I'm sure Desiree will make sure that you're OK. She is very efficient when it comes to answering emails, so put together a list of questions. That way, you'll get the answers right from "the horse's mouth." There's no such thing as a silly question, if the answer makes you feel more comfortable.
We dove a site called Tortuga Reef, and one called Barracuda. The current at Tortuga may be a little much for a newbie, so I don't know if they'll take you there. We saw well in excess of 30 turtles on that dive, but the current was around 3 knots.
Most important thing is to have fun. PDC is a great town.