The FDR and the CVR (flight-data and cockpit-voice recorders) are housed in the tail section, since it has the greatest likelihood of survival. They are usually recovered from fractured aircraft parts by hand. Removing them from an intact aircraft by means of a manned submersible would involve hours of work, and require tools and dexterity not available to current mechanical armature manipulation technology.
Kendra arrives at the cemetery, per A.J's request to retrieve the laptop. Her car is there but she allows the taxi to leave without checking the car for HER keys. There is no reason to presume she would not have brought her own keys, knowing that she would be retrieving her own car.