1. Nope. Also, bear in mind you don't actually control dragons when you fly them, it's pre-determined paths.
2. Nope. You can "command" the dragon to attack something but no control over your own combat.
3. They just meet up with you AFAIK.
4. No, it's considered a mount.
5. Yes, you can.
Please don't expect full on dragon flying however. It's nothing like that, and while cool you'll be disappointed if you expect proper mounts.