To US Residents: Resale License Question

Hi. I recently retired and am now playing a snowbird, spending my winter in Arizona. One thing I have begun to do is visit area flea markets, and I think I might want to try my hand at it. I plan to buy items at wholesale but know I need a resale license to do this. By the way, my last residence is Michigan, where I no longer have property, but still have a drivers license from there. Right now that suits me, as I have plenty of time to go until it expires, and am using a friend's address for insurance purposes. But, I will need to figure out a better solution before long.

I have been thinking of signing up for a mail forwarding service, based in Tennessee, because that state seems friendly to RVers -- although the sales tax would be hard on me if I lived there. Anyway, the question is: will I need to be a resident of TN in order to get a resale license from that state? Regardless, if I did get a resale license from TN, and never even made a sale in that state, I imagine I would still need to file quarterly statements.

Another, related newbie question: If I technically became a resident of TN, and earned my income entirely out-of-state, would I have to pay TN income taxes on that money?

Thanks in advance for replies.

Bruce