I have short hands and tight fists, so I rarely tip even in the US. As for luggage, I've almost always lugged them myself at any hotel that I stay in. The dive operators that I've use in Dahab and Sharm tend to be European run mostly with European counter and dive staff (and a sprinkling of Aussie and US), so the usual tipping/baksheesh phenomenon in Egypt doesn't seem to apply. They have a token one or two Egyptian DM/guides, but those at the dive operators I use never ask for tips and do not seem to expect it. In fact, I've found them no different than the European staff in that regard and equally pro. For the diving, when in doubt, ask the dive operator manager. Personally, if you want to tip, I don't think you need to tip more than your DM/guide. Maybe include the boatman if you're like the only passenger. Liveaboards might be different, but again you should check with the dive operator.