-Here is the source. 

You don't just pay the interest every month - unless you specifically opt for an interest only loan, but then you are missing the equity buildup which is a valuable source of return on your investment.Michael gave you the monthly payment on a 30 year loan.

This is what I would be living on as my major source of income.Rather than suspending/waiving rents for those tenants impacted by the COVID-19 crisis I recommend that New York state issue rent vouchers to cover the rent payments of those impacted.Here is a portion of the bill - Section 1.

Sourced it from digital marketing (he came to our site via SEO).I paid $45k for it and sold it for $225k within 4 months purchase to close. 

You may be better served to look at your internal rate of return which is the sum of all those sources of revenue - noi, appreciation, debt pay down etc. 

Should you, me or anyone reading this start down the road of real estate investing (With an iron Will to see it through, even though it will only ever be a source of income and a necessary, although not particularly enjoyed venture?)

Most real estate friendly mail providers will have a minimum of around 200, some even less, but it takes a considerable amount more to source deals.

The most difficult aspect of this was digging and leveling out the space...oh and removing quite a few roots.

I cannot point you to a definitive source confirming my opinion, but I believe that the definition covers any income on which you pay self-employment (Soc Security / Medicare) taxes.

The good news is; this downturn in the markets is from an external source and not economic related, so perhaps the downturn will recover quickly once the virus is under control.