I am planning to put down 20k and pay the private investor 8% amortized over 40 (do people structure this way usually?) 

As a leasing consultant for a property management company, I usually see tenants pay all utilities. 

Usually most MD sales are sometime in May through June.  

They usually require being renewed every 5 or 10 years and the bank can close your line at any time.  

I also would try meetup app, you can find house walk through and meets, usually without paying anything.Best of luck to you!

I usually shoot for 15% or higher.

The building was made in 1960.We're not entirely sure how much we should project for maintenance / capex every month, in order to make the right offer on the building.What do you usually budget on something like this?

UTLS  etc .. permits many CA locations permits can be 50 to 75k per home.. but I like building these days as a preferable to heavy duty rehab.. last comment is log home in your area unless your way up in the moutains above SD  its too hot and sunny those log homes will get weathered pretty badly and they usually don't fit in the scheme of what is going on in the area like say a desert style home with stucco etc.. that can handle the heat and sun

For example, B class building with B credit tenant will usually achieve X cap rate in the market where A class building with AS class tenant will achieve Y cap rate. 

Usually you get stuck paying cash for keys.