Hey Martijn,
I just got back from El Gouna, really an excellent place!! El Gouna is like a private town in the middle of the desert, filled with 4 and 5 stars hotels and resorts, it's clean and it has everything you need!!
* The beach at kitepower is the place to be, also for non kiters! there are many chill-out areas, 1 or 2 bars and a restaurant, alot of cool people and no locals trying to sell you everything!
* You can basically stay in any hotel in El Gouna and it will still be close to Mangroovy beach, some of the hotels have a bus that will take you there for free or you have a shuttle bus that passes every hour... I always took a Tok Tok (3 weels motor-taxi) it will take 3 to 5 min from downtown El Gouna to the beach and it costs 5 pounds per person (0.8 eur). I stayed at The Three Corners Rihanna Resort and it was just perfect!
* I didn't take the trip to the Island of Tavila (i think this is what you mean) because i didn't have enough time, they say it's really nice so I will go next time!
* I was there from the 9th to the 16th of August, had 2 kites with me, 9m and 14m... I could kite every day almost all day, the wind goes up and down during the day and it has almos always the same direction.
Here are some pictures of me in action in El Gouna....
http://www.kitehigh.nl/forum/index.php?topic=27151.0The website of KitePower...
http://www.kitepower-elgouna.com/en/el_gouna/el_gouna/ (i think you know it already but just in case ;-)
And if you need any other information at all just let me know!!
Gr.
Cris