bvbellomo
Contributor
Other bits I have thought about:
If you aren't already qualified in nitrox I would suggest gaining that qualification before you go. The diving on any of these routes is fairly intense, and generally at a depth that suits nitrox. With air is is fairly easy to run out of no deco time. Nitrox is often free, or at a fairly reasonable cost. You said you already have deep. Apart from those two I would suggest just getting diving experience before worrying about more courses.
If you speak English you won't find any language problems on most of the liveaboards. For the Egyptian dive guides English tends to be their second language. I have dived at a few German owned dive shops around Marsa Alam, and they will hold the briefings in English rather than German.
I am getting Nitrox certified soon. Without Nitrox I'd limit a group or a buddy who has Nitrox, something I really want to avoid. Nitrox also gets me Advanced Open Water, which some of the trips require.
I also plan on "Stress and Rescue", which along with 12 dives, gets me "Master Diver" and the 50 some of the liveaboard need. Depending on my time and budget, that might have to wait until after the Red Sea trip.
The official language of Egypt is Arabic. I haven't found 1 review, trip report or article on the Internet in Arabic yet, so I assumed everything everywhere would be in English. As a native speaker, I am torn by English taking over the world. It makes traveling a lot easier for me, but we lose culture and intellectual ability.