No, I'm positive he'll be in later episodes. Why else would he talk to Jack, and then be the only person in the part of the plane that Hurley bought out? He was emphasized for a reason.
Yeah hence my strong suspicions.

As for Ajira being front to something else, possible. Actually I'm going to class it as likely given that their people were apparently shooting at the Lostaways a few episodes ago.

re: explanations, I wouldn't say this is the first time that's happened, but this season has definitely had a lot more of that than previous years.