My wife came to US in 2001 and I came to US in September 2004.
In 2007, both of us had income as students in California. We filed jointly as resident for 2007 tax since my husband was already a resident.
In 2008, my wife was on OPT F1 visa first and later on H4 visa, dependent of me, and she had no income for the whole year. She had $2000 loss in the stock market investment from January to July 2008 when we were in California.
In 2008, from January to July, I was a student and had income in California; from August to September I worked on OPT F1 visa in Washington; from October 1st, 08 to December 31, 08, I worked in Washington on H1 visa.
My questions are:
1, should I file federal tax as resident or nonresident?
2, should I file California state tax as resident or non resident?
3, can I deduct my wife's investment loss ($2000) in the stock market both in federal tax and California state tax?
4, what is my filing status? "Married filing joint return" or "Head of household"

Thanks a lot for your help.

In 2007 you filed joint return as residents so you are resident for 2008. File joint return as residents. You are not head of household as you are married and have not separated.

For CA you are resident if you live in CA; states have different rules than federal.

If you file jointly, you CAN deduct your wife's capital losses in the stock market by completing Schedule D.