as far as i know, AI driver will perform the same (so Williams in Tier 2 etc...), but if you drive the Williams you will be able to fight with Ferrari and Red Bull. So the .ctf file modify the car for you, and the database modify the car for the ai.
yeah, thets right. The teams and AI performance will stay the same for the AI, but the Williams will be better for you.
For the AI maps it will work without the database, the only thing it that they will be slightly less agressive.