I want to learn from experienced landlords here, how much deductible should we choose? 

Hopefully you land another 5 year tenant this go around!

I am about to pay the land cash 500K, then build 10 apartments for roughly 1.5M.

It could be that the property wasn't built yet and it was a land purchase then the buyer bult the home. $5,000 is still pretty cheap for land though unless the land was bought long ago.

Landlord-tenant regulations are a bit complex in California and getting hands on is the best way to learn before expanding into larger investments. 

Numbers don't really work out for landlords though.

@James Wise MICHIGAN UPDATE: new law went into effect January 2, that landlords can no longer discriminate on tenant income source.

Off-market deals are key if you go this route, so networking is huge.Out-of-state investing is another option people love, especially in markets like PA (Philly, Scranton) or even down south where prices are lower, and the landlord-tenant laws are more forgiving.

Cost approach A straightforward method that adds the cost of the land to the cost of building construction.

Where did you take into account the landlord paid utilities?