I contacted a broker about two mixed commercial/residential units being sold individually out of a portfolio of 15 properties.

Not before that long it could become more interesting for you than for us here.Now, for us building a portfolio of rentals (and btw also an option for Americans), we avoid this by not doing it as an individual but with a company (SL) and changing it to company tax (first two years 15% and after this 25%) and creatively deduct way more costs.It is true though that this is a good way if your strategy is to reinvest your money time by time building something bigger/passing it along to kids/relatives etc, because when you want to take money out of your company you would need to pay dividend tax or in the form as a salary.   

The current flavor in the Denver metro area for up-zoning on individual properties is is "NO!"

They tell me it’s so easy to show individuals are behind them and can sue you if they wanted to.

I've noticed the forums provide a wealth of knowledge from individuals investing in a wide variety of strategies and feel this is the best place to start.

You should also network and find top-producing agents and real estate individuals to learn from.

@Ian Radcliffe Regarding your question, I think it depends on the individual.

I am using my own money, sitting in my checking account, and loaning it privately to individuals who I deem qualified to borrow it.  

Greetings,I am a 45-year-old individual seeking to expand my investment portfolio with additional properties.

This is completely up to you, If an individual came around with perfect credit and met your other income requirements I assume you would rent to that person.