Unpermitted structure in Cali needing utlity meters and more

[Vikram Deol]

Hello everyone, long time listener and lurker. First time rental investor. I am a realtor in Seattle but live in California and hung the sales hat for now. I got a pretty good deal on a 2 unit 1 lot property.
Front home is 3/2 in current setup, 2 livbing areas, garage converted poorly to a room, kitchen

Back is 1 bed, bath, living and kitchen unpermitted 

From what I have been able to dig up to get  the back strucutre permitted, I need 

•  2 parking spaces
• a gas meter 
• get unit up to building code 
• either site map or engineering map ( what would be difference other than costs? would I be able to get by with just a hand drawn site map from my contractor?

I wanted to go Section 8 on the property, but wasn't sure if it's possible either. 

Apprecaite the help in advance. Very excited to have finally stepped in to arena.