are you going to setup as a Corporation/LLC or Sole Proprietary ?
Sole Proprietary:
City Business License.
Fictitious Business Name
State Resale Permit (if you are going to be selling item)
EDD (for California) and Worker's comp if you have any employees
Corporation/LLC:
EIN Number (Federal ID Number)
City Business License.
Fictitious Business Name
State Resale Permit (if you are going to be selling item)
EDD (for California) and Worker's comp if you have any employees
Thats basically it. Even though it is an online business, you will still have a physical address and thats why you need the licenses since you are doing your "online" business from a physical location within a city/county/state.
EDIT:
If you are going to be making any structural changes, then you will need Zoning Approval. Basically, before giving you a city license, the city will tell you to get approved from Zoning. Zoning will ask if you are going to make any changes to the structure.
If you are going to, then you will need to first get a zoning permit, make the changes, get those changes inspected and only then zoning will give you approval. if no changes, then the person will take your word for it

and give you approval on the spot.
Business Personal Property form will usually come in ordinary mail within a few weeks of you establishing your business. You just fill out that form and mail it back.
Fictitious Business Name: You will need to go to County Office and file for it and will need to get it published in a local newspaper.
Resale Permit: You will need this if you are selling any item in the state. Basically, the state wants to collect sales tax on anything you sell for retail consumer use (unless you are selling to resellers, in which case, it will be non-taxable and your customer will be paying sales tax and not you).
Let me know if you have more questions.
You will ONLY need EDD, Worker's Comp, Labor laws etc if you are hiring employees.
Corporate/LLC Filings: If making a Corporation, then you will need to file with your state before you do anything else. You will need a corporation number before you do your city license, resale permit, Fictitious name etc.