They contact you shortly before your interview so don't worry about that bit. Accomodation will probably be at the Park Inn at Yas Island. None of the hotels are very busy at the moment so it'll probably be that one. It's pretty nice there.
It's all via email and you'll be emailed your tickets. Don't worry, it all gets sorted in the end.
With regards to Fellowship I would agree completely. There's lots of good and bad points. I've had a couple of blips along the way but overall I've found them to be friendly and able to offer you wiggle room.
The 777 fleet is good and most of the guys on it nice chaps although roster imbalances continue to be a problem. The airbus guys work very hard (but no more than some euro charter outfits) but only you can decide if life out here will suit you and at the end of the day home is home.
Good luck