What values get entered in Prior Depreciation and Prior AMT Depreciation regarding my vehicle? The amount it depreciated by? The value after depreciation? The %?

You can leave these blank.  If you claimed Actual Expenses for your Business Vehicle, TurboTax fills in Prior Depreciation for you.

If you claimed Standard Mileage, you will enter a Depreciation Equivalent on another screen.  You will need your total number of Business Miles to calculate this (see screenshots).

More info:

https://ttlc.intuit.com/replies/5809830