You'll find that most of the dives conducted in the Red Sea will be of a similar profile. Light penetration is good and you find the reef extends from depth to the surface. In fact, the most beautiful part of many reefs is in the shallow water when you get maximum colour from the light and a huge amount of fish life.
Topography varies from walls that drop to 800 metres (Shark Reef, Ras Mohamed) but there is often a fairly narrow slope from the fringe reef with some flat sandy parts in places but then heading for the inevitable drop-off into the Abyss. The Eastern coast of Sinai is much deeper than the Suez coast so there's more bottom and less drop, and then as you head down into the South of the Red Sea you are back in the deep water again.
Pretty much every reef dive we do here will hit maximum depth for only a few minutes and gradually shallow up. Some locations mean you are down past 20 metres for an extended time to see the best of the reef, but if you run low on air quickly, it's not far back to the reef plate where you can make your ascent and enjoy safety stopping in the amazing colours. Unless there is a reason to go below 30 metres, there's not a lot of point at most locations, because the best stuff is shallow. I very rarely even get there when I'm guiding.
A typical first dive of the day for me would be (Jackson Reef) 8 - 10 metres for 10 minutes slowly down to 18m after 15mins, turn around drop down to 27 metres for the Red Anemone and the black coral bush with the long nosed hawkfish, back up to 18m for the wall, 100 bar (30-35 mins for the average diver) up to 15m, 60 bar up to 10m, safety stop on 50, exit on 40, probably a good 10 - 15 minutes shallower than 10 metres in the north coral garden, which almost nobody ever goes to, for some reason. That's a kind of default dive profile for much of the diving here.
Different operators have different guidelines as to which divers they will allow to do what. There are local laws relating to maximum depth (30m unless you have Deep diver training), solo diving and decompression diving; beyond that some might say that you are required to dive with a guide if you have less than a certain amount of experience, but a guide is certainly handy to have around - cos we know where all the best stuff is, of course!
The Southern Safaris in St. Johns, or Elphinstone, the Brothers etc. are probably the most highly rated in terms of Red Sea diving, but they can be a little more expensive, it depends a little on where you set sail. You can also safari around Sinai and cover a lot of reef that the day boats don't get to.
Are you intent on the liveaboard? Most of the best stuff is accessible through daily dive excursions as well.
Have fun!
C.