In digging into the details through public record searches I find out that he has had 3 evictions, several drug convictions, and a violent crime.

I currently have a pre-tax retirement account with employer match and a Roth IRA invested in the stock market.

If you had a couple million in equities and a need to diversify your holdings by adding real estate, maybe.

It sounds like you've absorbed a bunch of problems already and a new sewer line and the current basement situation will cost you way less than the $50K in fees to sell it. 

I believe these systems only work if you have good employees, in which case a bonus is unnecessary.I provide strong compensation, some benefits like 401k, growth opportunities, and a strong work culture.

Also, if the LazyDog exits at some point, and a new tenant needs to come in - who will bear the architectural/remodelling expenses?

Last year was back to earth; a glut of available properties drove the rates down for everyone and a drop in visitors also increased vacancies.

That’s why you get a discounted interest rate and a lower downpayment, because owne occupant properties are low risk. 

$6k tax.Ins,hoa, not to mention utilities . took out a HELOC off of our personal home ( res.worth $900k, and a 260sq ft studio, mtr. $1450 mo.) for$ 220,000 for the deposit.

build to rent is great. they are an intermediary that help investors contract direct with turn key new build. they are pretty sophisticated we have sold a house so far and we are looking to sell other multifamily with them. there is a vetting process and as an intermediary they don't control construction they help vet builders and establish relationships. they have a big team. the other builder I've never heard of but unless you can see your house I wouldn't touch it. rent to retirement has a strict policy of 90 days until certificate of occupancy until they will send a deal out they are good at what they do and I'd recommend them. they have options all over the country and established relationships.