You raise several independent questions:
1. LLC vs. Corp: LLC is a very flexible and free form entity. That flexibility brings in a lot of complexity and overhead. The best solution is to incorporate as an S-Corp (S for small) - S-Corp gives you most if not all the benefits of an LLC in a very light weight. To be an S-Corp you need to incorporate and make an S-Corp selection with the IRS (if you miss the deadline you automatically become a C-Corp). S-Corp also prevents the need for restructuring when you get investments - post investment you simply switch to C-Corp with the same structure.
2. Delaware vs. CA. Most Silicone Valley, across the US, and even international Start ups are registered in Delaware - it became the common legal-framework for hi-tech, much better than to incorporate at a state level, where each state has different legal rules. BUT since we live in one USA, CA recognizes Delaware corporations (I believe all you have to do is to register/inform CA that you're doing business in CA - but you don't have to be a CA corporation to get the incorporation benefits (Imagine if that wasn't the case - companies would not be able to freely operate across state lines).
S-Corp and LLC both allow you to deduct expenses for your Startup against personal income. C-Corp doesn't.
One advice is to avoid registering millions of stocks because for some strange reason Delaware taxes you yearly based on the number of stocks (even without income). Each million of stocks cost somewhere around $30/y (not 100% sure). Heck, it's not like you need more than 1m stocks anyway :-)
3. From a tax perspective S-Corp offers one great advantage. You can issue Restricted Stocks that vest over 4 years, which are worth nothing at the time of issue, so 100% of the income from selling stocks later is capital gains). If a co-founder or employees leave before 4 years they can keep the stocks that vested, but the rest is returned to the company.
Disclaimer: I'm not a lawyer, nor a CPA, so all my above advise is based on advice I got from others (including internet research), so you should do your own dependent validation before taking action.