If you are working in CA, the tax is sourced there, even though your company is registered to NV, so you'll end up with an apportionment (allocating income/deductions between the two states).
Here are the forms:
Get the 100S Tax Booklet for S corporations, including all its forms, schedules, and instructions.
Thank you for your question.
The important part is that you withhold in each state as applicable...
I've personally seen W2's with two states (they have extra lines on them, and this is more common) or two W2's (payroll companies seem to like this...). That part really doesn't matter, as it is all the same in the end, just so that all amounts get reported correctly. Don't issue two W2's to the federal government, one for each state, as you'll make the feds think that the employee has received 2x the wages...
Your residency is determined by your permanent home. It is what it is. Your taxes are then calculated accordingly. A person's residency is ultimately determined according to personal facts and circumstances, for each applicable government potentially under audit etc., so file according to what your residence actually is. (general rule, your permanent residence is the place you plan to return to long-term, not a temporary work assignment)