Then I take out a commercial loan for ((market_value+1)-$300k)=$50-75k-ish,  buy it for market_value but only pay her the difference, somewhere in the closing docs have my mom "forgive" or "re-assign" the $300k loan, and between her and I we would have a separate agreement and I'm not sure of the terms.

., not sure if you're looking to do conventional financing, but if this is your first house and you are looking to do FHA, it'll probably be worth going through this program. https://www.biggerpockets.com/forums/50/topics/481...We did the listing agent route and it worked out for us.

You can offer to move them into the newly renovated unit at the increased price and with a standard lease.OR you can tell them that the rent is going up $50 every 6 months until it hits market and that you will be requiring a standard lease going forward. 

Are there any recommended cities/areas with good cash flow, that are relatively affordable, i.e 50-75k/unit?

50/50, 80/20, etc.?

I would ask this question in a thread which deals with seasonal markets, since you may get some creative responses.My market is technically seasonal (I do have 90%+ occupancy year round) and we evaluate properties with a 50% vacancy outside of the town I live in.

What are the exact rules here?

Not sure how they plan to enforce the 90 day rule because I am told airbnb will not release that info to them.

I know the rules on syndication is very complicated and very specific but I don't know what constitutes the difference.

That's why the 10 loan limit rule doesn't apply.Conversely, portfolio lenders do not sell their loans to Fannie or Freddie, so the 10 loan limit rule doesn't apply here either.