I, too am starting a commercial kitchen in Sacramento. You are two hours away so I don't think we are in competition so I'll tell you what I have been through. You can also read my blog on this site which gives some really ugly details on what you may go through.
First, on your choice of location. If you want to do a warehouse you have to check with the city to see if they will allow it. Many industrial areas are zoned for some office/business sq. footage in the warehouse, but I found that they have requirements for lots of the space to be used as storage.
Second - equipment there or not? If you go into a space that already has the hood, gas lines and plumbing then you have to deal with making your design fit with the existing placement of said hood, gas lines and plumbing. You can move things around, tear down walls, etc. I haven't figured out if this is a cost savings because all the places I looked at would require significant modification to work for me. The issues with going from the ground up are cost, cost, cost and making sure you have handicapped-compliant entrances and bathrooms. I'm looking at a 2100 sq. ft. shell (building with no interior walls) and suspect it will cost me around $125,000 to build it out. No matter what you do, get as much tennant improvement money as you can to offset your costs.
I'm putting in a 8x8 walk in refrigerator, 2-6 burner gas ranges, 2 convection ovens, a 20qt. mixer, food processors, table top mixers, immersion blender and the usual smallware. I should mention that I'm putting in two separate workspaces so two chefs can work at the same time... thus the reason for two of most things.
Yes there is a lot of demand for this type of business. Here in Sacramento there is one shared-use kitchen. The owner only wants people who need her space for 15+ hours a week. She charges $2,000 deposit and refunds only $1,000 when you leave, keeping the rest for wear and tear. I don't know what she charges monthly on top of the deposit. I talked to her about the issues she has - mostly it is chefs who get possessive of the kitchen equipment and have arguments. I am setting my kitchen up for hourly use. No one can have more than 15 hours per week in my kitchen because I'm really setting it up for the little guy who wants to make their custom cookies and needs a commercial kitchen. Granted I won't make as much money as if I did the shared kitchen thing, but being a caterer myself I know how tough it is to find places.
Rent - The usual amount I see is about $25-$30/hour. Frankly I don't see how people can charge so little and keep their heads above water. Maybe they own their building so they don't have to pay rent, but with normal lease rates of around $2.50 sq. ft. I can't make my rent and insurance and pay for equipment.. you get the idea. I charge more than they do.
Look at my blog for more info and check my web site for what I offer - Steel Magnolia - Certified Commercial Kitchen Facility For Hourly Rental in Sacramento
. You are more than welcome to email me if you have more questions.
Oh, and marketing. All I've done is put up my web site. I have had around 30 hits and people are still calling to find out when I'll be open. I plan to put up flyers at my local community college and have joined the local restaurant association to provide some more exposure.