Hi,
MY PD for EB2 is Oct 2006. I have I-140, EAD and AP approved. My AOS (I-485) approval is pending. My AP will expire in March 2010.I also have a valid H1B Visa approval till April 2011 but my H1B stamp in passport has expired. I am maintaining my H1B status currently.
I want to travel to canada on official trip.
My Questions:
1. Do I need to stamp my H1-B visa in canada or Should I use Advance Parole Document? What is the disadvantage of using AP?

2. Will I loose my H1-B status if I enter US using Advance Parole Document. Will I have problem in renewing/extending H1-B visa if I use AP to enter US.

3. Are there any possitive effects if i stamp my H1B visa in canada.

4. I want to maintian my H1B status after using AP for travel. Is it possible?

Thanks,

jp