One thing I've learned from my experience is that I do not set hard rules.

Any advice or shared experience would be great.

What you want is an agent with experience who knows how to negotiate, watch your back, navigate difficult situations, understand contracts and law, provides an objective cross-check, etc.

I do not have experience with above ground but I believe that would be fine if done tastefully. 

We have sent over a few referrals to him and they have given us great feedback when we asked how their experience has been. 

Rent control in the bay area can be extreme as many areas have rent control in excess of the state mandated rent controlIn general experience RE investors are not choosing to add a single ADU in single family zoned areas.  

Do you have experience with STR? 

Again, the BiggerPockets store has some books on this topic, or you can learn about it by watching podcasts, reading blogs, and interacting on the forum.

DM me if you want to discuss my experience as either an investor or a lender.Jeff

From my experience you should expect a 10% to 15% of gross revenue for repairs/maintenance.