TimHenn,
what kind of live bait: depends on what your fishing for. Tinker Macks, Snappers, Porgies, Bunker, Bergalls, Spot (if they come up that far) all work on Fluke, Stripers, Blues, Mako, etc.
how much: Depends on how long your fishing for and how many predators are around. Bluefish will destroy baits. Depending on how large the baits are and how many you need/want...figure 1 fish per gallon of water. More if the fish are smaller. The live well should be constantly on and the flow should not be pushing the bait too hard.
when: whenever they're available...live baiting is great for the larger fish.
Try not to handle the bait as they will live longer if not stressed/de-slimmed.
Hope this helps...