You can definitely get an interview with internal recs and without attending a job fair.
The junior domicile is Orlando. However, I believe you can get Denver or Orlando straight out of training. You might have to wait a month or two to get into Chicago. Junior captain is definitely Orlando.
F9/NK merger talks have picked up again, but I really don't think it's happening within 5 years. Frontier will go through an IPO, which is probably a year away, and then they will probably see how the stock does for a couple years before they even look into a merger. With both F9 and NK growing and making lots of money, there is no reason to merger. Wait until there is a big recession, or a big hiccup in the industry, then merger talks will get serious.