Would that affect the sellers disability or social security payments?

In my experience, the agent has been the catalyst for other vendor referrals including attorney, contractor, inspector, tenants, etc so selecting one that you feel is well experienced in this space will help you to connect more dots.

The landlord effectively refused your request, since March rent is included in her 'options'. 

This was included in the initial contract we signed when we put the $1,500 deposit.

If you're interested, I have a partner network for STR investors that includes those specialties.

If I do end up purchasing a duplex for 299k, I would be living in one for about a year and rent out the other at 1300/month, In which I would still be paying out of pocket for the mortgage (est. 2122/month as per zillow) not including the other expense.

many people don't necessarily have the time or skills to do their books*REI specific tax efficient advice to include business structures, 1031, depreciation, deductions, etc.  

Our current portfolio:-Florida SFH: Mortgage (includes HOA and PM company) = $2100.

Feel free to ask questions and tap into the resources available including the informative BiggerPockets podcast.

'Despite attempts to communicate with the tenant since December, including two attempts to arrange key collection on the 29th, I've received no response.