how to change passport

My passport has been extended once. I was told I need to get a new one after another five years. Now it is the time to do that.

Can anyone tell me if I can keep the old passport after I get a new one, since it has all the visas and my GC application has records of my old passport.

How early before the expiration shall I send out the application?

Shall I go to SF consulate if I live in the Bay area?

Many thanks,