I am curious if I should analyze this property as a normal multifamily, in the sense that I should consider a split multifamily with 3 separate houses to be the same as one building with 4 units inside.

I would normally do exactly what you said, except, I'm so cheap, I'd probably end up doing all the painting myself and paying the savings to my chiropractor after throwing my back out! 

What is your cost to build 850 sf ADU, compared to your normal 2,000 sf build?  

I've purchased a number of properties before and I'm familiar with the process through normal RE channels.  

It takes time and flexibility which 9-5's don't normally allow for.  

If you can save for a 20% contribution you may be able to utilize HML for a flip that would hit numbers to allow you to refinance out of the HML and into a normal mortgage to house hack...but you will still need to yourself, be able to qualify for that mortgage. 

Difficult for any normal retailer to compete.

I have read more than once that mistakes and fear are normal.  

Not that that couldn't happen with a small unit too, but I love that our normal guests are a couple or maybe a small family so turnovers generally go really smoothly.

Normally, you do a title search before the auction.