and it occurs to me that the NX-01 should not be in the game if this is the prime timeline.
In First Contact, the E goes back in time, defeat the Borg, and come back. No Borg in the past in the Prime timeline. in Enterprise, they discover Borg in the Arctic. Ergo, Enterprise must be the alternate timeline, the one the E left to return to the Prime future.
No to T5 Constitution No to T5 Miranda No to Arc Yes to a Federation Frigate Pet