We've had a bit of wind recently, not unusual for March, though mostly from the north so it doesn't greatly affect sea conditions. The wind is cold though, and with wind chill it's very cold as you get out of the water. In case there is still wind, bring a baggy nylon top that you can easily put on over your wetsuit and don it as soon as you're back on the boat - makes a tremendous difference.
Last week we did have four days in a row when boats couldn't go outside the reef. One or two large boats did, but no-one elected for a second dive.
Water clarity varies a lot with depth and weather conditions. Recently it's been as poor as 30' and as good as 150'. Reckon on 50'-80' on average. Come with a flexible attitude - there'll be days when diving is contra-indicated, so be prepared to do something else. Best not to buy a pre-paid dive package unless (unusually) it's refundable if you don't dive.