However, my lender said that I cannot use an FHA loan because the building is comprised of 4 individually zoned town homes, meaning they can be sold individually.

Ultimately, if you are looking at purchasing more properties I would recommend looking into the Series LLC, as you only have to publicly file the "parent" Series LLC and then you can create an unlimited number of "child" series under it - each offering the liability separation of individual LLCs when operated correctly. 

Obviously, you would not do this if you did not have a good backyard.Market research indicates that renovations, and subsequently, "indoor/outdoor living", are very popular right now.For a personal perspective, would it be worth it to put these types of products in a Class B home, in a Class A or Class B neighborhood?

Like it was said above, that is a very positive indicator you are onto something good. 

That will further give you an indicator if he will pay on time.Hope that helps

Solo 401k are for self employed individuals so it won’t work when she is an employee of the business

I did reach out to Cozy and their response was more along the lines that once the tenant initiated they would have to return the funds to tenants bank but advised that our individual lease agreement should speak to this as chances are the landlord would have to pursue legal channels to recover money justly owed. 

Are you talking MF properties (multi-family ) or individual condos ?

The individual I am referring to contacted me via telephone, if that makes any difference. 

The individual I am referring to contacted me via telephone, if that makes any difference.