1) find a unit that you want to join and hunt down their DO/CC and ask if they have any positions open. If you're having a hard time contacting someone, use your officer recruiter.
2) it'll be up to the unit if they push for a upt waiver. Keep in mind, joining the ANG/Reserves doesn't happen over night. It took me 9 months from the time I was hired in the interview to the day I stepped in the unit. I had 0 delays in paperwork, just had to wait on the damn scroll. If your serious about switching, I'd suggest getting with a recruiter ASAP and getting all your paperwork organized so that when a unit says they'll hire you, you're ready to go.
Lemme know if you have any other questions.