Here is the scenario:
Tiefling with racial trait to have a Bite natural Weapon.
Said Tiefling is a Druid with feats Improved Natural attack(Bite) and Weapon focus(Bite).
These feats improve his bite attack.
Now our druid beast shapes into a wolf that has a bite attack too.
Question is: is the bite attack in wolf shape of our druid improved by the feats INA and WF that were learnt for his Tiefling bite ?
They weren't learned for his tiefling bite. The same as a fighters WF(longsword) is not learned for a specific sword.
The feat represents the character knowing how to bite more accurately when making bite attacks. It would apply to any/all bite attacks he makes.
INA should work the same way, it should increase the step of the wildshaped bite.