I used a computer too, wrist mounted is OK.
I have been told that you can bring your own shorty IF it is brand new with the tags still on it. The concern is contamination of the tank with ocean pathogens. This would likely only benefit people with very hard to fit frames.
The first time I did it, the shorty they gave me was small and I ended the dive a soprano. The second time, I requested 3x (the typically eyeball you to see your size and weighting requirements).
Also, watch the weight. They tend to overweight everybody and there are no buoyancy checks. For new divers, it can be a little overwhelming, since it is a shallow profile and you can yo yo around for a bit, you are weighted by someone else and then herded into a group dive with other divers, many of whom are very experienced. I did it several times and each time, at least one or two divers had major buoyancy issues (and one diver never managed to get underwater at all). Also, I go to Epcot frequently and always go and watch the dive groups go down...invariably, several people have major issues. The DMs ask for a C card, but that's it. It doesn't seem to matter to them if you haven't been in the water in ten years, or even did a salt water dive at all. As they say, it is a fairly difficult dive to botch, given the controlled surroundings and the abundance of athletic, experienced handlers around you at all times.
No concern about air use, however. If you run out before everyone else, simply surface and they toss another tank on in minutes.
One warning. It's easy to drift around and forget that some big -***** sharks with open jaws are finning about. I was daydreaming looking at the bottom and a set of razor teeth passed by my ear. The DMs say there have been injuries to absentminded or stubborn divers (not giving ground) who have been lacerated by the sharks' teeth accidently.
