Dermotaxi

If you activate the ability, but there's no exiled card to reference (perhaps because there wasn't one in any graveyard to imprint), the ability does nothing. Dermotaxi won't become a copy of anything.

The imprint ability is linked to the activated ability that makes Dermotaxi a creature. This means that the second ability refers only to the card exiled by the first, even if it becomes a copy of something that later exiles other cards.

Dermotaxi does not have a crew ability. Activating the ability to have it become a copy of the exiled card doesn't count as crewing a Vehicle. If a creature you tap to activate the ability has a triggered ability that triggers whenever it crews a Vehicle (such as that of Gearshift Ace), that ability won't trigger.