Hi,
I am on H1B in US, I am getting Canadian PR in another 15- 20 days. I understand that I will have to go to Canada with in 1 Yrs time. What after that?
Can i come back and stay in US?
1) If yes, for how long?
2)What will I have to do to keep my Canadian PR valid?
3) How often will I have to visit Canada?
4) Will I have to get Revisit Visa to Canada every time?

Hope to hear any relevent Information soon.
Thanks in advance

You will find most of your answers on the CIC website.
Refer:
http://www.cic.gc.ca/english/irpa/fs-residents.html

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"Mah deah, there is much more money to be made in the destruction of civilization than in building it up."

-- Rhett Butler in "Gone with the Wind"

You need to be resident in Canada for 2 years in any 5 year period to keep your PR alive. If your place of work is anywhere near Buffalo / Detroit / Seattle / Spokane you can probably maintain residence in Canada (pay Canadian taxes too..) and commute to work in the US. But then the border delays could make that impossible.