Sorry no one replied to your post sooner. I haven’t used the 3.X rules in two or three years now, and hopefully one of the posters more versed in this ruleset can give you a better answer.
Here are the bonuses I see for a creature in DCC #2 being transformed into the Dragonkin:
+4 to natural AC,
+4 to melee attack,
+10 ft to movement,
+1on fortitude saves,
+4 on both Move Silently and Search skills,
A breath weapon doing 3d6 damage. The type of breath weapon depends upon the form of dragon,
Immunity to both sleep and paralysis,
And immunity to the form of energy that the creature has as a breath weapon.
Here are a few links to other threads on the Goodman Game forums that pertain to this fine module:viewtopic.php?f=20&t=783viewtopic.php?f=20&t=2568viewtopic.php?f=20&t=2946
The middle one is my attempt at DMing this module.
Anyway, if you have further questions or comments, please post them and we’ll try and answer them.