I distinctly recall them asking Don West what the A.C. colony was like which means that he had been there before. Again, from what I understood he is a crew member that goes back and forth to ferry colonists to their new home. Besides, even if this was the first shipment of colonists they had to have gone to A.C. before that to check it out for being a viable planet and to set up some basic infrastructure for the colonists, so maybe he was part of that crew.
Yes, he did. Which means that the Resolute ferry station is the only ship with the stolen alien drive they are using to go back and forth. What I don't remember without rewatching it, is if the aliens stole it back before opening the portal. I think they did, which means the Resolute and the Jupiters attached to it are goners, along with earth's means to get from Alpha Centauri to earth and the other way.