So they basically did rental arbitrage on your property for 7 years and then walk away. 

Basically you stay working there and rollover funds into another qualified plan.   

When you talk about replacing income, the safety of that cash flow is much more imperative, since presumably you are living on it, too.And then you combine both thoughts: safety in income stream to live off of, and cap rates/yields from assets.  

It will familiarize you with the basic terminology and benefits.

I got a quote for 8K sft retail from a construction company for around $120/sft, this includes site prep, utilities, metal building erection, exterior finishes, interior insulation etc (basically build the shell from scratch).

Basically any brokerage will want to have you on.

Since my bank account had no funds (I transfer them fully as soon as rent collections deposit), Baselane basically paid those refunds from their own pocket and now are coming after me to recoup them.

Buying a single-family home can be a great starting point for new investors to learn the ropes and property management basics.

Fences, basic landscaping, tree removal can put some nice padding into your margins as well. 

I've been told by the insurance companies/brokers that a basic Homeowner's or even a commercial policy will not do.