Cool idea!
Great script, I'm trying to learn how to do stuff like this. But my idea was you have the players start with an egg in their pack, okay, and you can just hatch them like that. Also, have a kind of battle system, make it to where players cannot attack other tamed dragons or cast at them, yet when their dragon enters combat w someone else's, it opens up a gump with the dragon's current spell ability, and some misc. other special attacks that you can teach them. You should also be able to give your dragon special items, such as gear and potions, to beef them up a bit (a special vendor for this). But, anyways, the battle system can be done it turns, thusly making it more fair. Also, maybe if your dragon kills another dragon, it gets like a bonus 500 kp per the dragon's evolution level.
I hope other people like this idea, and maybe you can edit it around.