California has some of the most restrictive building codes in the country.

You might find that there are restrictions you can't live with like prohibitions on parking a camper, boat or commercial vehicle - and even the colors you can paint your doors or shutters.Be sure to ask whether there are any pending lawsuits against the condo association or any special assessments in existence now or anticipated in the future.You shou;d also request a certificate of good standing from the condo association, meaning that the seller doesn't have any outstanding fines or fees. 

Also HELOC's get more restrictive or lenders get rid of credit lines all together.

We were able to obtain a second FHA loan for a triplex even after renting for 8 months (no time restrictions from 1st to 2nd FHA).

Let's say however the ByLaws are clearly not specifying any restriction and you already own the property, I'm 50/50 on asking the HOA permission first then. 

Second, what’s the story with property investing in AUS given the astronomical purchase price compared to rents and the newly restricted lending policies at the major banks?

Depends on the type of mortgage and the restrictions in your note.

Most lenders will be more restrictive then what the guidelines allow for.

You have to be the one to impose the deadline and stick to it. 60 days at most.

I caution you though that there is more than zoning that can affect building plans, like deed restrictions, easements, setbacks, floodplains/ways, and the list goes on.