Tax question from TN & US resident

[jade]

Hi,
I have a few questions on how to file our tax 2004. I have been a resident alien in US for years. My spouse is a Canadian citizen. He worked in Canada Jan-May 2004, and had tax deducted from every paycheck. Then from May 2004 to present, he lived & worked in the US on TN, and do not have residence or dependents in Canada in this period.
1. Regarding my spouse's Canadian tax: he should only report his Jan-May Canadian income to Canada, and as a Canadian resident. Right?
2. Regarding our US tax:
1). Should we file jointly or separately? If we file jointly as residents, we'll report my whole year income & my spouse's May-Dec income (but not his Jan-May Canadian income). Is it ok? In this case, can we still use standard deduction?
2). The fact that he became a US resident for tax purpose in May 2004 means that he'll report his world income to US starting from May, not January. Am I right?
3). Can he file as Dual Status Resident? Does he have a choice of filing as Dual Status Resident or US resident?
4). If he file as Dual Status Resident, we can't file as Dual Status Residents jointly, and I'll have to file separately, right?
5). My spouse has some RRSP. Should we report it on US tax? Since there's no increase in this RRSP, is it ok if we don't report it?

We got a headache trying to figure all this out. We'd appreciate any advice you could give us.
Thank you.