For a scope like yours, it typically takes 2-3 months with a solid GC, though sometimes supply issues can stretch that out.

Be aware of any local regulations in Emeryville as well.Please make sure your 4plex isn't exempt from AB 1482.

The regulations in Chicago can be quite overwhelming, so I’m looking forward to exploring the opportunities in this area. 

Your definition is correct for "legal non-conforming".The "legal" part of "non-conforming" is dropped when it doesn't apply so most commonly people call these units "non-conforming", "finished", "in-law suite/unit", or "bonus unit".Non-conforming: Any property that doesn't meet current zoning requirements.Legal non-conforming: A non-conforming property that was lawfully established under previous zoning regulations and is allowed to continue its use.Based on his posts @Mario Morales is referring to a non-conforming unit.

Use some for buy and hold (I personally would prefer apartments rather than buying a few single family homes) and some for lending/trust deed investing.In either category, you must know what you are doing, know how to vet the investment, how to vet the sponsor (if investing in a larger fund of some sort), the laws and regulations on the lending side, how to investigate which areas to invest in buy and hold and notes/trust deeds for that matter.So as you have already said several times, lots to think about . . . 

This covers the vacancy time and work supplied to find a new tenant.

If existing houses are cheap relative to land and constructions costs, and supply is high, it may not be worth developing even if the agency says "do whatever you want".

There's a to unpack here - preparing the property, pictures & listing, finding a management company, taxes, regulations for the area etc.

I'm hoping they get a good director in place who wants to serve their customers (tenants who need safe houszing) and their vendors supplying that need (landlords) and operate an efficient and successful program serving our community. 

Navigating NYC's zoning regulations can be complex @Jon Pflueger, especially in M1-2 districts, which are primarily designated for light manufacturing and commercial uses.