I am currently going through business permit

Make sure you do an OPRA request to check for open permits and confirm with the town whether the 2/1 below is legal and permitted.

You’ll want to check if your specific work falls under their home improvement contractor licensing, or if there are additional local permits required depending on the county.

You must get a permit, drill holes in the bottom, demo the bondbeam down a foot or so, and then fill with compaction inspections along the way..... last time I checked it was about $10,000

I like both of your ideas so I would look for the single where an ADU is permitted or one with a dump ADU to renovate (that's best) and balance that against the purchase of a 2-4 unit.

Registration is only permitted for legal entities, partnerships and natural persons who are 18 years or older.

GC never pulled any city permits yet charged me (didn't find this out until the job was finished). 

Duplex have different zoning that may permit additional units.

And I have below clause in the leaseRental Application: Only those people indicated on Tenant’s rental application are permitted to reside at the Premises, with the exception of any minor children born to, or adopted by, Tenant.

I'm an Architect and MRED Grad and have entitled and permitted over 200 units across Bay Area and Norther California, ask me anything about SB9 or ADU design / permitting