Aloha,Over the years I have worked with a pretty wide variety of Owners, large and small.

Your questions cover a wide territory.

I wish I had better news for you, but it is a wide spread problem from my experience.  

For example every week I see listings with bedrooms less than 7' wide.

We are trying to fill in a rather wide wealth gap

I've searched far and wide for cash flow positive multis in hoboken and JC, and have yet to find a cash flowing property (my goal wasn't to cashflow but to net my monthlies as close to 0 as possible).

I found the renovations costs to vary widely and a couple of contractors said it costs X amount of dollars with no line item estimates (red flag there).

. - I am all for a city-wide Chicago ADU ordinance. 

Not hairline crack but a continuous crack probably about 7-8 feet long and wide enough to put a credit card into the crack. 

They often offer competitive pricing and have a wide selection.- Online retailers: Amazon and Wayfair are good for smaller items like hardware, as you've mentioned.