I’ve heard that the federal government has set a limit of 10 mortagages per person.

Yes section 8 can be harder to scale because the government has many requirements for units and there are tenants who don't pay sometimes. 

Government would have by now after 100+ years passing law to stop building homes.  

If I might throw on my optimism hat though, once they fully move all of the SEAL teams down to the new Naval Coastal Campus from Coronado, the government's attention to the issue *ought* to be higher than ever considering that these guys are out in the water a lot and when you have a state-of-the-art training facility for our elite forces being influenced by polluted water, this becomes a national security issue.  

Coverage will vary by local, city, county, state governments, but some examples might include requiring sprinklers, upgrade electrical wiring (older homes can have aluminum wiring which isn't used often anymore at least in CA), electrical panel upgrades, insulation / energy value requirements, different fire place construction

My goal is to slowly grow a portfolio at 1 to 2 per year until I have 15-20 properties by the time I retire from the government at 50 years old.

There are CT state laws governing what amounts of lead time are given on a cancellation. 

I do not understand the relationship between tax returns, borrowing money from banks, and limiting the taxes you pay to the government.

As a general statement, anytime you're dealing with government bureaucracy things can sometimes get frustrating.

The IRS example is for people using the HELOC to pay for non-income producing activities.The theory is that generating income typically generates more tax revenue for the government.