In somce other areas we have invested there have been zoning issues with the muncipality. 

This plays into the affordability issues for tenants by allowing them to live in nicer neighborhoods for less money, yet I get monthly revenue comparable to short-term rentals.I have also shifted my focus to buying better.

By emphasizing your qualifications as the basis for your decision, you steer clear of potential issues related to discrimination.

Ask for the zoning department.

Other than cost overruns and unforeseen issues, I think it's just a question of if this is worth it.

I’ve worked for some group home providers where they employ a maintenance worker who handles some of these issues (usually if the have multiple homes in a specific geographic location) and I’ve worked for homes where the handiest employee fixes things and that option doesn’t always have the best outcomes.

The only issue with seller finance and resale is if they don't want to receive a payoff in short order, then they should include a pre-payment penalty. 

I have probably done between 80 and 100 lease options and we haven't had any issues with litigation or anything.

I do, however, see you regularly posting regularly on LinkedIn, in a similar fashion to your posts last year here on BiggerPockets.Normally, this would be an issue that I'd move on from and not waste my time on.

In general it is not worth building a single ADU for a variety of issues but the largest is the cost to add the ADU is typically far greater than the value added by the ADU.