The assets are always managed by a particular management company - but what happens if the operating/management company folds for whatever reason? 

Some property management companies specialize in STR's and that may be a good option for you.

A 401k is typically offered by a company, i.e. your employer. 

Even if you were an employee of the company a savvy SEC attorney will tell you that you need to be paid a salary and not commission based.The promote point has been addressed so I will not add to that.

I am a homeowner who purchased my first home two years ago trusting a real estate agent (assigned by the mortgage company) who did not seem to have my family's best interest in mind.

I also have an apartment building with co-investors, managed by a PM company - haven't had any problems (so far).I gave examples of horror stories but also there are millions of investors who do well and don't have these nightmare issues.

We use Fresno Management Company.

Could he enter into partnership with us forming a whole new company where he contributes the property as equity and then we refinance the property at the price we agree on and we use that money to pay him as a silent partner.

As a side note, I know there can be some issues with a landlord "acting as a utility company".

The top sponsors for Real Estate meetups are lenders and title companies.