There's several members of the unit that are currently serving - I myself am one of them - as well as numerous ex-military. With regards to Phase 1, it's still the same process. This is just to make sure that everyone receives the same standard of training prior to joining the unit. Real world experience is useful, but there's things specific to Arma that still need to be taught.

As for LOAs, the unit is very accomodating for things like exercises and deployments, and the general rule is 'Real life comes first', so if you have events coming up that you need to LOA for, you should be fine.