So, I've got a difficult tenant.The main point is that he hasn't paid rent since September. 

.)- Average days on market- Absorption rate- Historical data on rents and sale prices in the area- Population growth- Main economic drivers (industries, individual companies, etc.)- Crime stats... if you know specific zip codes/submarkets that you'd like to target, the best data will come from local precincts. - and more..I'd recommend remaining active not only here on BiggerPockets, but in other valuable RE investment networks that you can find - i.e. local meetups (meetup.com, eventbrite, BP local events). 

Principle pay down and appreciation are the main drivers behind my strategy, and I focus more on IRR instead of cash flow.

The problem is that they are not knowledgable enough to understand that the analysis is inaccurate, but start making investment decisions based on the analysis anyway.That is one of the main problems I wanted to solve with DealCheck by providing a tool that takes most of the guess work out of running analysis calculations and evaluating rentals/flips/wholesale deals that will satisfy 80%+ of investors out there.But going further, I think that tools like DealCheck are perfectly viable even for more experienced investors.

Normally I would agree but if we are renting out the main house I don't want them paying for the ADU. 

I am a mainly cashflow person. 

The Columbia market -- specifically West Cola, Cayce, North Main, toward Camden, etc. -- appears to have some properties that would cash flow well, but may be limited on long-term appreciation.I'm looking to stick to market-rate properties.  

Yes I do understand a majority of people don't think its a good strategy mainly because of the turnover, the risk, the lack of equity. 

I have personally stayed in one of these places where the main house is separated, and only the basement space which has a walkout entrance, its own kitchen, and two bathrooms would be rented out an Airbnb.

You might find that installing a mini-split system, properly insulating, and ensuring the finishes match the main home’s quality will make a difference in how the appraiser views it.