I am transitioning from IRR to ANG after being off AD for less than a year. Do I really have to go through MEPS again?

Per AFI 48-123 any member who wishes to enter active duty after a break in service (understood to be active service in which you received regular physical examinations) must undergo an initial enlistment/commissioning/aviation physical (paragraph 3.1.8.2) For shorter breaks, a copy of the most recent physical exam with AF 422 would suffice. Hope that helps.

I'm not a recruiter, but I do work with ours frequently, I also come from the medical side of the house so familiar with the documents you have to gather.
Typically, if there is a break in service, members are required to go through MEPS. I am under the impression that IRR still counts unless you've completed your 8 yr commitment.
Of course, the advice to work with your recruiters is the best advice so far :)

I don't believe you do. If they need your MOS or somewhere within the state you are good to go.