I have put in multiple bids on condo/ townhome style homes in the area (housing market here has gone crazy). 

In Texas, we have a government agency called TCEQ (Texas Commission on Environmental Quality).https://www.tceq.texas.gov/This agency regulates things like underground fuel storage tanks.

I'd like to perform some BRRRR style cash purchases rinsing and repeating with a starting investment of $100k. 

I'm looking into moving to Chicago in about 6 weeks and would like to start investing in RE ideally BRRRR style.  

.- Permits and Fees (Includes Entitlements, Utility, Plan Review, Inspections, Any required studies, Reports, Environmental) - Reach out to your local municipality or whoever will be providing your permit.- Financing/Taxes and Holding costs - Talk with the bank that you have your home mortgage.

I think finding what interest you and give the challenge you are looking for while being able to provide for the life style you desire is completely personal. 

I do see that masonry cleaning/chemical wash (the prep work) - "may require an air pollution control permit from the Environmental Permitting and Inspections Section of the CDPH"And then digging further I see there's also a separate Architectural Surface Cleaning Permit could be required.Anyone have experience with this?

Here's how it works in Indiana.Indiana is a tax lien state, Big-up auction style, One year redemption period. 

Based on your experiences, would you pick one style ADU over the other? 

Sure, some people may not prefer the style choice, but overall, it's been a win for us and has helped us stand out from the crowd.This house was a huge win for us.