The dragons in DragonVale are leveled up by feeding. There is no difference between species, only by how many treats they have been given.
There is no such thing as a Birthstone Dragon on DragonVale
As of July 2012, there has not been a star dragon in DragonVale.
You don't breed a Kairos Dragon in DragonVale. You have to get parts to complete it.
The incubation time for a rainbow dragon in DragonVale is 48 hours.
To date, there is no grass dragon in DragonVale. You may be thinking of the plant dragon. See the related question.
love dragon and panlong dragon
Sonic Dragon and Flower Dragon
Brass Dragon and Fire Dragon
Fire Dragon and Lightning Dragon
Water dragon.
a earth dragon
Breed a Crystal dragon with a Cactus dragon.