Oakland tenant friendly laws and tenant occupied duplexes

[Gulnoza Bobokalonova]

All, I am very often finding duplexes that have both units tenant occupied in Oakland, CA. 

1. Is this the usual deal? 

2. I have asked Redfin agents to get back to me with 'buying out' options about current tenants and never heard back from them. I am wondering now if it is even possible in Oakland to have tenants move out with a new building owner? 

3. When investing in duplex, I will have to invest as 'owner occupied' and live there at least 1 year in order to have lower downpayment. Does it mean that I can only be looking for a duplex that has at least one free unit?