Hi Luv2Dive,
I've regularly been diving Coz for 18 years, so hopefully I can shed some light.
Yes, Coz is essentially entirely drift diving (technically it's live-boating, but the distinction isn't critical for this discussion). The boat will drop you off, you'll drift with the divemaster leading, and the boat will be waiting when you surface as group. It's the greatest--no fatiguing finning, no navigational nags & lots of reef gets ridden.
The current typically runs from the SE to the NW, and at about a knot or two, but it can hit 3 or 4 knots. Usually you can fin into it, but not for long. Going with the flow is where it's at on Coz. Many Coz newbies have concern about drift diving, but few remain so once they've tried it.
This is not to say it's always a piece of cake. Occasionally wicked up & downcurrents appear, and these take some special skills to handle. Very, very rarely you just get roller-coastered along out of control. In fact, some years ago our own Dr. BillP & some others got into one of these on Coz & ended up getting a couple of chamber treatments. You may want to read my Undercurrent piece on dealing with such currents. It's accessable by going to this URL--->
http://www.undercurrent.org entering downwelling in the search box, and clicking on entry #2. If you have trouble, let me know. It's the DM's job to keep you out of these, and they're quite good at it, although occasionally rogue currents pop up out of nowhere & there's simply no preventing having to deal with it.
Of course, what reefs you do first depends on a number of factors, such as where the boat went yesterday & the day before, where the majority on the boat wants to dive, where the best conditions are that day, the Captain's & DM's moods, etc.
Some nice reefs that are not too deep or right on precipitous walls include Dahlila, La Francesa & Maracaibo Shallows.
Go, relax & have fun.
DocVikingo