I'm actually in charge of the hiring board at our unit this year. We're interviewing next week. Just some thoughts off the top of my head. We hire both from within & off the street at the same hiring board. We go out of our way to make it as fair as possible so no one group (prior enlisted folks within the unit) have an advantage over enlisted applicants outside the unit or civilians applying with no prior military experience.
As far as applying to multiple units goes we encourage it. It shows that the applicant has the drive to really serve/fly in the military somewhere and we explain to them that the culture is different in the units throughout the country and the fit may or may not be good at one particular unit or another.
I will caution you about the way to get to the airlines comment. If discovered during the interview that that was the premise for applying to the unit then that would most likely result in non-selection. We need people willing to serve with the understanding that they may be called upon to give their life for their country. The Guard is way different then in the past and we just cannot afford to hire people whining when asked to deploy for up to six months at a time in some of the armpits of the world. I get it. I'm a major airline guy as well but still deploy when called upon without complaint. ( OK without complaining much!). Our unit's philosophy is your family comes first, civilian job comes second, and the Guard comes third UNLESS we get activated then those priorities need to change. Sorry so long winded. Hope this helps someone.