The one tenant / one check rule keeps it clean on your end.

With HELOCs, each bank can (and do) make their own rules. 

This would violate the following prohibited transaction specifically:“Sale, exchange, or leasing of property between a plan and a disqualified person.”https://www.irs.gov/retirement-plans/plan-particip...What is more, this same rule applies to round-about/straw-man transactions.

A lot of states require the 2 year rule, although I would check in the PM part of it, some(although very few) don’t require a real estate license to do PM

They exist to enforce rules to protect property values, ensure a clean, safe, functional neighborhood, etc.

3) without zoning restrictions how do we determine best unit fit for property?

Investing in multi family (4+ units for example) has very different rules than investing in single family homes.

It seems as though many programs or older or carry many restrictions. 

Don't forget the utilize the 70% percent rule and to subtract your rehab costs to determine your purchase price.Using independent wholesalers may give you the opportunity to find better priced deals, but you'll have to do much more leg work to qualify the leads as these groups will not hold your hand as much as the aforementioned. 

@Steve RyanIRS rules prohibit you from pledging your retirement plan as collateral for a personal loan.