Welcome to BP.I'm based in SECT so I don't have an answer for you on this one, but I do know that CTREIA, the statewide investor association, has a very active Fairfield County rehab subgroup.

I found this information about qualifying property:https://www.law.cornell.edu/uscode/text/26/1400Z%E2%80%932(i) In general, The term “qualified opportunity zone business property” means tangible property used in a trade or business of the qualified opportunity fund if— (I) such property was acquired by the qualified opportunity fund by purchase (as defined in section 179(d)(2)) after December 31, 2017,(II) the original use of such property in the qualified opportunity zone commences with the qualified opportunity fund or the qualified opportunity fund substantially improves the property, andI'd like to zero in on this sentence:"The original use of such property in the qualified opportunity zone commences with the qualified opportunity fund"Does this mean one can purchase a new build to qualify?

Similar to you, we'd like to do a 640 sq ft unit (the max allowed in SMC) and are looking at homes with this goal keenly in mind.Are there any hidden traps, things we should be aware of going into this, or things that you wish you had been able to better plan for?

or of personal freedom through real estate investing so you have to start somewhere.If you try to learn everything you need to know to effectively help people in every situation you will be trapped in the learning cycle and never feel comfortable actually talking to people.

Its scary because new investors who trust the wholesalers and don't really do as much research can really get trapped in a bad deal, leaving them with the mess of trying to figure out how to get back in the game on top. 

Finding a lender trapped by an old insurance policy into paying a fixed rate and at the same time forced to lend at a lower rate due to market conditions is like finding fleas on an iron dog.

To clarify, the house isn't in section 8: the tenant is.

That way you are not trapped there.  

There were several times worth of toilet clogging and unable to flush (the plumber found a toy in the P-Trap and newspaper the other time).

The sill plate is solid 10"x10" fir beams. even with years of water/insect damage it still has more life in it than the treated 2x4s you see today.