All of the things you've mentioned related to preserving medical job opportunities, vacation, etc. make me confident in the following statement:
Regarding vacation, I can only speak for what I've seen and heard in the fighter world, but it is quite commom depending on your CC, DO, or WO. You're in an upgrade: don't take leave. You have to projo a TDY: don't take leave. We have an inspection to prep for, there is a base exercise, etc..dont take leave. I know a lot of bros that have lost leave due to these very things (myself included). I also know a few dudes that said, "F that noise my parents have never met their grandchildren so I'm taking leave to go see them." They were taken out of the upgrade, set as the lowest priority, or screwed in their next assignment. All this because they didn't show enough "commitment" based on when they took leave, or that they took it at all during the above events.
My point is, this is not how the guard operates. This mindset of screwing over ppl for living their lives because it causes the bobs a minor inconvenience is one of many reasons if I could do it all over again I would never go AD. I'd go straight to the guard. You can still do TFI if you want to dip your toes in to see what active duty life is like.