No dragons
No they are not.
No, DragonVale dragons are not able to be traded.
You can't win in dragonvale, unless you consider collecting all the dragons a win.
You feed them dragon food.
level 10
The dragons in DragonVale are not trainable. You only feed them to level them up and breed them.
You can use Sonic and Lava Dragons or Air and Quake Dragons
Results of current and tree dragons can be mud, crystal, or seaweed dragons.
No, you can only breed directly through the DragonVale app.
Storm
There are actually a couple of dozen gemstone dragons in DragonVale. They are a type, like the fire dragons or earth dragons. You would need to know which gemstone dragon you were trying to breed to find out who the parents should be.