If things don't go as expected, an eviction is quicker and less expensive than a foreclosure.

That's a healthy expense.

Further, if planned well, you can have lots of operating expense deduction.

The only items affecting capital gains are basis and expenses of sale. 

Real estate is extremely expensive in the area.

But if “by doing” he means investing without first having the knowledge to KNOW the risks, EVALUATE the risks (and potential rewards) and to TAKE ACTION to reduce the risks then the cost of this learn by doing education is probably going to be significantly more expensive than a degree in real estate from MIT, let alone reading the\ree or four texts on your own.  

Plus, with fewer building structures to upkeep compared to apartment complexes, your repair expenses remain relatively low.Mobile home parks also have the potential for high returns.

This is generally necessary in any commercial real estate deal as a lender is your least expensive investor - meaning their interest rates are significantly less than what your private investors want.

Your children can inherit the property as well.I think you will owe transfer tax on your QCD and fees for the trust and LLC as expenses to keep in mind.

Might be tough from area to area, but I typically find that homes built before 1950 that were converted from single to multi family are 9 times out of ten - a full gut rehab and way too expensive for first timers.