Where to begin? (Norcal Rural Multi-Use, New Building)

[Joe Landvin]

Greetings!  

I have an opportunity to arrange/coordinate a unique small project as a launching point for a land development venture.  I have a bit of general real estate knowledge, but not much experience at all.  I am truly humbled to have access to the vast volume of information and community of experts here in BiggerPockets!

I have a contact that owns a home on multiple acres with an additional casita / mother-in-law house built on the property.  The property is semi-rural in Elk Grove, CA (out of the suburbs but still a neighborhood with 2-3 acre lots).

The owner wants to build a 3rd building on the property as multi-use.  Would be used as a warehouse for events, with restroom but not a full kitchen.  It would be fairly large, 2-levels, in the 7k sf range.  Assuming I have a rough sketch and a builder already, what suggestions do the developer pros here recommend to get this project going?  I really do not have a strong idea of where to start.  I assume calling the building department but what do I even ask?  Is there a specific podcast episode or article as a good reference?

1. Zoning?
2. Entitlements?  I am guessing since it's already occupied by two buildings, this is not an issue but I want to go through the steps / proper channels since this is a warm-up practice for future development opportunities.
3. Permits?
4. Other considerations?

I sincerely appreciate any help or direction from the smartest minds in the industry.

Thank you!