Appreciation of an asset with low down payment, tenants paying principle down, tax advantages, all reasons why real estate is an investment of DOING.   

You might get these days 60% leverage so you'll likely need 40% down payment plus reserves and the financial institutions will want you to keep those capital reserves in their institution.If you are a new investor, there's a couple of opportunities to get started. 

If you do, could I ask how that has been going and has the rents been comparable to the payment standards advertised by the respective housing authority?

so those owners are pretty comfortable - no mortgage payment - and they don't need to sell, and they don't care where an investor "needs" the price to be to make money. 

If it’s verbal, they’ll need to document any prior communication or payment records to establish the relationship.If the PM is completely unresponsive, they may want to send a formal written demand for communication and payments via certified mail.

Rent was due by 5th but no communication on late payment and is not responding to my text/emails. 

What property management software or tools would you recommend for tracking rent payments, leases, and maintenance requests?

I use Buildium for tracking rent, fees, leases, and collecting online payments, but I don't use their reports for much, as I end up copying my online banking each year into spreadsheets.I've been using Rental Hero for the last hour and already impressed with it.

What % of purchase price is smart to put as a down payment? 

I assume you currently have a residential mortgage that does not have a pre-payment penalty.