You should absolutely make sure all costs are factored into the NOI.

One popped up in my neighborhood and several people in the neighborhood informed code enforcement and they shut them down.If you and your wife are good with living in a smaller place to pay down your mortgage faster than that seems like a great idea to me.At some point in the future you could always move back into the main house and rent the smaller unit if you ever wanted to.

They are glad about the gym, refuse, water(if included) that is factored in.

When I was analyzing deals in the Private Equity sector, I saw everything from 26% - 42% IRR needed depending on the size of the company managing assets, additionally how many Management/Fee company's are factored into the business model and at what point in the expense model they're collecting fees.There are payroll, Marketing, Office space, etc... now a part of your business model, acquiring an asset for cashflow becomes a small part of your equations. 

I wonder if it will bring mainly 'blue collar' jobs to the area.

I think the main question I have for you to figure out is this: What would you need to do to increase your rents above your estimated $3,000? 

In most cases this requires a capital expenditure that should be factored in a Comparison analysis. 

We own a few rental properties but our main focus is on residential remodel and sell (flip).

Many won't lease to an LLC and, even if they do, they will look for a personal guarantee as well negating the main reason to use an LLC.But, if you find the rare one that will lease to an LLC, you will want to go that route for asset protection and the tax advantages under the new tax bill.

That will take a lot of time away from my main business...but I'll learn a lot and hopefully make some coin..