There's a few things I do to make my batteries last longer; turn off real time auto focus, keep the dispplay off untill something intrigues you, and turn off the camera's flash (since you have strobes this is probably set already). I also do not pan or zoom the lense. With the rechargables that come with the camera I can shoot for two to three dives, but in no where near freezing conditions. The expensive, throw away, NiHilades, I think, last 8 dives or more, I've taken these on two day trips.
For shutter lag, you can turn off auto focus and set a fixed distance and the lag will be much less, but the shots are almost always slightly blurry. With the Oly (and most others) you can hold down the shutter release half way to get a focus lock, then snap when the "pose" is right. This is next to impossible to do underwater with gloves on but I sitll try.
Like anderon said, pan, and anticipate your target's moves. I have better success capturing a fish when they are in a path somewhat towards me, rather than when their path is perpendicualr to my own. I never try to peer into the viewfinder, and hold the camera a good distance form my face, looking at the LCD display and my surroundings at the same time. This makes it easier to anticipate my subjects path.
