You tell the airline what days off you need for mil, and they clear your schedule. If you have PBS, it's typically easier to get it pre-assigned before the bid, that way your airline schedule is built around the mil leave. They should give you some virtual credit for the mil leave, ie not try to cram 90 hours of flying into 25 days.

Basically non-issue on the airline side. Mil schedule would depend on unit. Do not commute to both mil and airline jobs, that will suck.

Both. Diversity of relevant experience is going to be better than more of any one thing. You already have the 121 ticket punched, but do you have previous military flying and what type?

If you don't have mil wings, you *might* get to the majors faster by building 121 time rather than taking a time out for UPT and seasoning, but getting mil wings is going to make your progression to a legacy almost assured and on a more predictable timeline.

If you already have mil FW experience, then you might be better off focusing on 121 flying for now (from a career perspective). Majors know that drilling reserves can drop orders to evade first-year pay and seniority, so you might get hired faster as an ex-mil guy vice a drilling reserve (then join the guard/reserves once you get settled).