I own a small multifamily commercial in Albuquerque and can confirm the diversity of the economic and cultural factors that you mentioned. 

Having all Section 8 tenants may cause you to have a higher cap rate on your exit due to a higher headache factor surrounding Section 8.

I've read BiggerPockets' Real Estate Investing book and am particularly interested in the house hacking strategy, as I'd like to move out of my current living situation.Our main dilemma is choosing between a single-family home (renting out one room to a close friend) or a multifamily property like a duplex or triplex.

Note that the diagram doesn't consider tax implications—that's another important factor you'll need to include in your decision.

They'll want all the money spent on the main house, lenders kind of ignore ADUs it's weird. 

Most of the designers I have have sort of a baseline price i.e $2.50/per foot but it can go up or down on other factors

I've included an example below to help illustrate this.So different lenders have different rates (which do vary even for DSCR loans) but these are factors they all consider.See example below:DSCR < 1Principal + Interest = $1,700Taxes = $350, Insurance = $100, Association Dues = $50Total PITIA = $2200Rent = $2000DSCR = Rent/PITIA = 2000/2200 = 0.91Since the DSCR is 0.91, we know the expenses are greater than the income of the property.DSCR >1Principal + Interest = $1,500Taxes = $250, Insurance = $100, Association Dues = $25Total PITIA = $1875 Rent = $2300DSCR = Rent/PITIA = 2300/1875 = 1.23If a purchase, you also generally need reserves / savings to show you have 3-6 month payments of PITIA (principal / interest (mortgage payment), property taxes and insurance and HOA (if applicable).

This reminds me of how Alex Hormozie describes "the value equation"; Experience in this case is the factor that determines the likelihood of achievement. 1,000%Alex Hormozie is one of the greatest marketers not just alive, but ever. 

There should always be timeline contingencies factored into each projects specifics.

Before finalizing a decision to sell, I thought I’d get some thoughts from the BP forumThe only obvious factor I know to try to head off a problem is to carefully screen applicants.