My empire is considerably smaller than yours but, so maybe is my attention span.

Forget the yellow letters because those all say the exact same thing and we got 6 in the span of 4 months.

It was a quick simple purchase basically to get some equity built over a 10 year span.

It also depends on the time span.

Your capex budget should include roof 25 year life span, floors 10 year life span(carpet only 5 years), appliances and hot water heater 12 years, hvac 20 year life span, bath and kitchen remodel, 20 year life span, etc. 

I have little background in investment other than having parents who have owned a couple of investment properties over the span of 15 years.

I would compare over long durations (multi decades if possible) so as to span several RE cycles.

How much of the life span these houses have?

(I'm would like to get financing for 60 to 80% of the house cost if possible, so I can acquire more properties in a shorter span of time)3.

I'm not too familiar with peerstreet, but I'll definitely consider looking into it if you can get returns like that in such a short time span.