Tax help

Here is my background:
– married
– joined the military out of MI. Had a MI license plate, MI DL, MI voter registration
– wife is from OH. OH license plate, OH DL, OH voter registration
– moved to SC and bought a house. I (stupidly?) changed my HOR to SC. Apparently MI exempts state income tax for mil. Wife recently moved down with me and swapped her OH DL to a SC DL and was/is in the process of swapping her license plate and everything else to SC since its our HOR.
– I work in SC obviously and my wife is about to start her work in SC as well.

1. Did i make a mistake swapping the HOR from MI to SC? I feel like i did since we had to pay state income tax. Also, my wife is telling me there is a $250 registration fee for her vehicle since it’s from another state and she already had to pay an annual property tax on the vehicle ($200) to SC.
2. If so, can I swap back to MI as HOR? And if i can, can I somehow make a retrospective change and receive refund on some/all the fees I paid?
3. If we swap back to MI, what DL should my wife have? What license plate should both of us have? Does any of it matter? I assumed the important thing is for me to have a MI DL?
4. If we swap back to MI, what state will my wife pay state income tax to and what address will it be paid to?

Neither of us live in the HOR address nor will we ever live in that residence ever again (but plan on moving to MI and buying a house when we eventually get out).

1. Bonus: is there like a legit military tax attorney or tax accountant that i can talk to about this? I did the free military tax filing this year and it was literally an e4 cook who said this was her first time filing taxes for other people.