Triple country jeopardy

[triplecountry]

II have a unique (at least I think) situation. I am hoping someone can answer my questions.

I am a Canadian citizen in the US on a TN. In the US, I have been filing 1040. In Canada, taxes are deducted at source on any income from investments and I receive NR4 forms to use for for filing US taxes.

I have made plans to go to India for an extended period (many months) to spend time with family. I do not hold an Indian passport, but I hold a certain kind of visa status (given to people of Indian origin) to live and work in India indefinitely. First part of next year, I plan to return to Canada.

My current employer in the US has asked me to work remotely from India for few months to finish up some projects.

Questions -

1. Do I need to file a sailing permit before leaving the United States?
2. Do I need to make any changes to tax withholding status in the US? Does working remotely from another country subject me to some higher tax withholding?
3. For tax year 2008, do I need to file 1040NR? Or can I file 1040?
4. I suppose I will need to let the fund companies in Canada know of address change to India so a different tax rate can be used to withhold taxes. How does this affect my 1040 or 1040NR for 2008?

I don't even want to think about tax situation in India at this time. I think their tax year does not even lineup with ours here.