Any insight or knowledge would be appreciated this way:  A mortgage and note do not, in fact CAN NOT legally prohibit the sale of the subject property; nor can that document REQUIRE the announcement of that sale.  

Typically, you just require that the property be vacant for closing.

Also, was agent required for it?

No idea on the notice period required, depends on your lease and your particular state laws. 

The larger property will be required to be held in an LLC.

The most important thing to do is either you or your wife need to qualify as a real estate professional (IRS definition, no realtor license required).

You can file annual reports as required in each state yourself and pay the fees.

It will require 15-20% down though as others have said.

We find ourselves receiving a combination of PDFs, excel spreadsheets, banking statements etc which then require reconciling and organization on our end.

Reflect on what you envision for your retirement and assess whether you're prepared for the effort required to manage properties in a new market.