Live view for stills is a useful feature on this camera. The first SLR I have found this to be so - as shutter lag is minimal.
The standard flash synch is 1/250th (but you can change it to 1/320th in custom setting e1 and still have TTL. Coral fluorescence, D7000 + 60mm AFS. Nauticam housing, 2x INON Z240 strobes, Glowdive filters. 1/320th @ f/9:

Although the camera does not have a dedicated AF-ON button, you can assign the AF-L/AE-L to be AF-ON, which at the same time disables the AF function of the shutter. This works in both normal shooting and live view and it is a good way to shoot in live view - stopping the focus from hunting and giving you a push to focus function. However, we found it has too much of propensity to hunt to use it during filming while shooting video. As Peter says you can also hear the button being pressed on the video! For stills it is fine - as you wait for it to be focused then shoot.
Alex