yes you would need Itin# for your wife to file as married.If your wife is here with you in n US then you file as married.
But if your wife is back home then you file your wife as dependent in another word she does not have income and is not a resident or a citizen and have not reside with you for at least six months.
However, it is possible that it would be more benificial to apply as married filing jointly. There are more tax breaks filing married filing joinlty.
if you deciede to use your wife as a dependent and you do not have any other depedents, you cannot file yourself as a head of household. Only if you have a qualifying child, you can file head of household. A wife being claimed as a dependend does not allow you to file head of household.