does apple care cover a cracked macbook pro screen?

You can try and there is a VERY slim chance it will, if you can inequivocally prove the damage was not caused by mishandling or abuse. Else it will cost you about 30-40% of the price of the computer. You might be able to replace it yourself for a bit less, IF you're handy with tools.

Doubtful. The only way it could cover it is if it was clearly a manufacturer related defect. If there was any user accident, the warranty clearly says it does not cover that. The cost varies by location. Call around. In the U.S. these places are often cheaper out of warranty to repair it:

http://www.dttservice.com/

http://www.powerbookresq.com

http://www.microdocusa.com/

http://www.macspecialist.com/

http://www.techrestore.com/

And this place offers do-it-yourself instructions also for people out of warranty:

http://www.ifixit.com/

Cheaper would be to add an external display.