A tibbit (Dragon Compendium Volume 1 21–25) possesses the natural ability feline transformation that "is similar to the spell polymorph but with a number of key changes" that allows a tibbit to assume the form of a house cat. The text explains many of the effects of the transformation, yet ends by saying, "Aside from the changes noted here, a tibbit's abilities and game statistics otherwise remain the same" (25).
However, the 4th-level Sor/Wiz spell polymorph [trans] (PH 263) has two other effects: a creature that employs the spell polymorph upon changing form regains hp as if the creature had rested for the night, and a creature that employs the spell polymorph sees its type changed to that of the new creature whose form the original creature assumed.
Does a tibbit's natural ability feline transformation likewise allow the tibbit to regain lost hp when it assumes house cat form? Similarly, while the tibbit is in house cat form, does the tibbit's creature type change from monstrous humanoid to animal?
Note: An upcoming PC may be a tibbit bard who can, while in house cat form, cast the spell alter self due to the Savage Species feat Surrogate Spellcasting (39). I want to make sure I'm determining correctly what forms are available to Grayboots when he's in cat form. And if the healing also occurs, that's kind of important, too.