QWhen playing this follower's "Whenever you drive check a Trigger" ability, if I can't select an enemy enemy on the field, can I still choose option 1 to have nothing happen?

ANo. If you can't select an enemy follower, you would be required to choose option 2.

QWhen attacking using a follower with Twin Drive, if I reveal a Trigger with the first drive check, do I resolve the Trigger before or after performing the second drive check?

AYou resolve the Trigger first. For example, if you reveal and resolve a Draw Trigger with the first drive check, you will draw a card, put the resolved Trigger into your cemetery, then perform the second drive check. If you choose not to resolve the Trigger, you will put it on the bottom of your deck, then perform the second drive check.

QWhen do "when(ever) you drive check a Trigger" abilities trigger?

AThey trigger when you resolve a Trigger revealed by a drive check. If you play a follower's Twin Drive ability and resolve 2 Triggers, any "when(ever) you drive check a Trigger" abilities trigger twice and become pending. Then, after you finish resolving the Twin Drive ability, you resolve any pending abilities.

QDo I resolve Twin Drive before an opponent can play cards and abilities with Quick?

AYes. When attacking, all abilities that are triggered must be resolved before non-active players can play cards and abilities with Quick.