Kaji Sahab, You can pay state tuition fee as soon as you get your green card which will be after one year of submitting application. And about living separately, just make sure you include your wife's name in the apartment lease and get one of the utility bill in her name. And don't get an apartment in her name at other place where she lives. You could do vice versa. She can show she lives temporarily at other place but permanent residence is one place for both of you. This way you won't have problem showing INS that you guys live together. My friend did this before so I know this works with INS.