Logistics of co-authorship for assisting business
This may vary by field, though common sense suggests some general applicability. I'm in CS and will offer my personal experience. 

You raise a couple of independent points. 

Does their affiliation/experience matter? Not in the least IMHO. I saw a paper at a strong conference with a high school student as coauthor!

Do they merit coauthorship? 
I'd say if they simply provided data, likely not, but you've already asserted they go beyond a simple acknowledgement. And you can certainly involve them enough going forward for there to be no question.

Seems to me you've answered your own question. But if you specify a field and someone in that field says no, you can't possibly publish if you aren't somehow credentialed, it's another story.

Good luck!