3.65 - 3.68 are the rates found everywhere. Dirham is pegged to the dollar so it shouldn't fluctuate, and I believe the official peg is something like 3.672 dirhams per 1 USD.

Don't exchange money at the hotels as they will bend you over on exchange rates. Either use ATM's, credit cards or go to one of many exchanges around.

As for FaceTime, it works on household Internet connections without VPN, but I echo TP - get Witopia - $60/year option. No issues whatsoever. I use magic jack also with Witopia and have a US phone number.