Military spouse who would like to incorporate small business.

(1) As you live in California and will operate the business from California, you are subject to California taxes. It may be simpler to form the LLC in California. The LLC does not need to be formed in a state where you have residency, so you may want to form in Delaware or another state that has certain LLC advantages; however, you then still have to register as a foreign entity in California while you operate from here and will pay California taxes. Because you move often, it may be worth further investigation if a Delaware (or Nevada) LLC may be an advantage in your case. Your CPA can advise on this. I often insist that clients have entity issues reviewed by their CPA to confirm those choices for tax purposes as I am not a tax specialist.
(2) Yes, you can have multiple DBAs and will need to complete paperwork for each.
(3) As for the "location of the company", if you mean the primary offices, you would use the current business address. If you are drafting an LLC Operating Agreement, rather than putting a static address, you can indicate the business address will be where the members elect it to be from time to time and note any changes in the margins. I like the flexibility of this type of approach for LLC Operating Agreements and corporate Bylaws regarding various provisions because it avoids unnecessary later revisions; however, standard agreement forms generally do not provide for this flexibility.

Disclaimers: The preceding response is a generalized response to a posting with limited information and is not considered specific legal advise or intended to form an attorney-client relationship. Rather, the response is a generalized educational response concerning the general subject matter of the post. To obtain specific legal advise regarding your situation, you should consult with an independent attorney in a private meeting where more detailed business information can be obtained.