I am seeing more and more investors vertically integrate as they scale without adding any additional human capital.

Creditors can't force the sale of assets within the LLC, preserving their integrity and protecting the business/real estate.

But, it only said that I could be fined and possibly put in jail if, (I act as a real estate professional without following the guidelines and meeting the relevant requirements).

And my feeling is for MOST people Solo 401k is sufficient to meet their needs, and an actuary creating a custom plan is “overkill”.  

Same as @John Underwood @Madheshwaran R..Usually it is to check if they are interested in bookings that I couldn't meet due to either no availability or the rare occasion when and AirBNB and VRBO booking for the same dates at the same time.

If you're looking to network and meet potential investment partners, local meetups are probably the best way. 

or show the property to interested tenants and ask them to apply if they meet the criteria?

I'd look in your local area for meet up groups, get to know some people, and be patient.

Or in the case of appliances, who meets the truck, checks the products and signs for them?

Once a taxpayer meets the REP status, do they need to materially participate in each property?