Many of your questions like parking can be answered there.https://www.sanjoseca.gov/business/development-services-permit-center/accessory-dwelling-units-adus/parking-requirements-and-exemptions

This did not cover JADUs only ADUsNote the use of the words SHALL and MAY giving this requirement to the discursion of the local agency. (6) (A) This subdivision establishes the maximum standards that local agencies shall use to evaluate a proposed accessory dwelling unit on a lot that includes a proposed or existing single-family dwelling.

I run a company that specilizes in creating legal accessory apartments in the local regions.

I think we are going to eventually see more ADUs (An Accessory Dwelling Unit, usually just called an ADU a secondary housing unit on a single-family residential lot) in the future.

In parts of san diego you can add quite a bit of value by adding Accessory Dwelling Units to a multifamily zoned lot (whether 2 ADUs or a dozen or two). 

Has anyone done it before? Care to share experiences? Cost, rentability, etc. Thinking of doing it to either a house or find MFU with garages (although it has been hard to find).Thanks in advanced!

Detached Accessory Dwelling unit

@Diana Smith Accessory Dwelling Unit - also sometimes referred to as a "granny unit" - which is a secondary unit on a property where a single family home resides.

Our expertise ranges from multi-family homes, accessory dwelling units to commercial properties.

There is 1 accessory dwelling unit registered on the street at number 702 (http://gis.montgomerycountymd.gov/dhca_acc_apt/)....which is different from a multifamily property.