She can earn a little income by the interest she charges you, and any value you add to the home is hers really if you default.

Hey Yasin, Do you have 2 years of income to show?

My ideal scenario involves acquiring a 2-4 unit property or a single-family home with an ADU, enabling me to leverage rental income to qualify for a larger mortgage.

A couple of things I would have done differently would have been to keep my W2 income as lonnnnnnnnnnng as possible, like longer than you think. 2nd would be do wholesale or sell more in the start rather than trying to keep everything possible as a rental. 

That's another problem, I'm surviving on a small fixed income, therefore I can't afford to do any true marketing.

house hacking has been mentioned here and I'd 1up for that as well, for sure the best way to get your first property, but in generally the path you are on into the brokerage and scaleable income is the way to go and what I wished I did right out of the gate.  

Look at the demographics of your specific location to see if the rent is within 30--40% of income level. 

When adding the rental income for Unit 2, it asked for % sq.ft. rented out.

Is it important to have the cash reserves already saved up BEFORE you acquire a rental property, or is it okay to just set aside a percentage of your gross rent to fund the cash reserves after the investment property is acquired?

Prioritize constructing long-term wealth, striking a balance between immediate rewards and long-term objectives to generate passive income and lasting wealth.