The events are defined as LUA_CBR_FUNC.
The ones that are not available are:
LUA_CBR_FUNC(pre_shoot, ctx, 500)
LUA_CBR_FUNC(post_shoot, ctx, 500)
The first two are not yet available from ML core. For pre_shoot, we don't know yet where to place a hook in order to do something useful from it (such as update exposure settings, or prevent the picture from being taken), so it requires reverse engineering. The post_shoot hook is a bit ill-defined, as it's a bit hard to tell when exactly a picture is finished, especially in burst mode. Currently, most ML code uses the QuickReview screen to tell whether a picture was taken; the recent Burst module looks at the file number property from Canon, which appears to work fine.
The last 3 are from LiveView vsync hook, which must be fast; otherwise it can interfere with image capture, possibly resulting in corrupted frames. Since the pink frames still appear during raw recording, it's probably best to keep those disabled, unless there's a good reason to use them.