Re: Liscense question?
You'll need to check with your particular state, county and perhaps city. Rules vary all over. Google "Business License" or "Starting a business California". You'll probably get a link to a state website that will lead you through the process.
A couple states to the north, I needed an EIN from the IRS, then a business registration from the state which made me visible to state and federal tax departments. My city license was a simple fill in-drop off. All totaled, about $200.
And some people are more reassured if you can tell them/show them you are licensed and/or insured which is a whole 'nother Oprah. That implied legitimacy is the main benefit of licensing, IMO.