#1: Yes, my wife and I did go Scuba diving in Sharm. There's a PADI diveshop on the Ritz property. I believe there's a diveshop in every hotel. The Ritz diveshop is run by Massimo. You go for a check dive just off the hotel waterfront and then you can go to Tiran island (day trip 2 dives) or Ras Mohammed Park (1/2 day trip 2 dives). We did 7 dives each, it cost us US$ 750 for the 14 dives plus equipment rental. The diving is really beautiful there.
#2: We felt very safe in Egypt. It might be due to the strict laws or the unbelievable police presence @ the major tourist places. There's a AK47 toting policeman every 100 feet in Cairo.
#3: We took the bus from Sharm to Cairo. The bus fare is LE55 per person, the journey is 5-6 hours. The buses run almost every hour during the daylight hours and 2-3 times during the night. It was a very comfortable journey. The 2 bus companies operating the buses are East Delta and SuperJet (We took the SJ).
I have posted my comments about the Sheraton hotels I stayed @ in Egypt, on the Sheraton board, if you are interested.
Thanks