, it is likely that human driving will be illegal on many roads. 

I've heard recently that the State of California passed a "ADU" law (Additional Dwelling Unit) which allows for a conversion of a garage to another livable structure.

I will not develop property unless it cash flows in year 1.(.58 acres with 3,000sqft min per dwelling so 8.42 dwellings or 8)Land Cost: $25,000 ($3,125 per unit) - Hoping this land cost is what gives me an advantageConstruction Costs: $706,270 ($85 psf construction costs) - This isn't a hard quote yet and will be updated once I get it officially quoted.

She helped me cancel my original homeowners insurance and set me up with a different company for Dwelling and Fire insurance (landlord insurance?)

Then a dwelling fire policy is written (with out liability) for the rented building. 

How much will it cost to obtain a  permit for this 2 unit dwelling's modifications?

You are not going to be able to buy a QUAD priced at $160K if they only lend you $100K.If you go to larger multi-family unit dwelling you would be a passive investor as you are a beginner you don't bring much value to the table apart from a keen sense to learn REI.

Rent control does not apply to SFRs, but it might apply if that SFR has a guest house and considered an additional dwelling unit.

From what I can read in the tax code it seems possible with the homestead exemption here:This annual exemption is available for “residential property that is occupied by its owner or owners as his or their principal dwelling place, or that is a leasehold interest on which a single family residence is situated, which is occupied as a residence by a person who has an ownership interest therein, legal or equitable or as a lessee, and on which the person is liable for the payment of property taxes

Again, take in to account this may not be his fault and try to treat him like a human being =) You'd be surprised how many times people take their frustrations out on agents when it's their decisions on pricing or not fixing/updating!