Where do you live? Living in base can improve your QOL ten fold. Outside of commuting you want a company that allows the flexibility to trade or bid for trips that will allow you to do your bachelors on the road. I would personally stay away from smaller companies due to the unstable regional industry turning on a dime and I would go somewhere that doesn't have a stigma attached to it. Whether the stigma is rational or not doesn't matter. The quick upgrade is nice but your not doing anyone any favors by accepting such poor treatment.

I would go to the airline near your home town or where you can stand to live first, then search for info on their contract and find out where they roughly stand in the pecking order, and then I would consider the anticipated movement.

I wouldn't tell them about your vacation in the interview. Worst case scenario call in sick, doctors note, and buy an airline ticket. I wouldn't post photos online of the trip and I wouldn't tell anyone at the company after you get back. You also just posted the exact dates of your trip on a huge website that a lot of airline people see. I would be very careful what details about yourself you give out on here.