To answer your questions:
(1) Yes. It's about the quality of your work experience, career focus and academic ability
(2) A little less so simply because the majority of applicants are Euro-based, and each country has different standards that may not be directly comparable. As such, the GMAT is looked at a little more closely.
(3) Neither an advantage or disadvantage. It's about the quality of your experience, irrespective of who you are or where you're from. It's not about diversity for the sake of diversity, but about quality first and foremost. If your experience is middle-of-the-road, it's middle-of-the-road.
Alex Chu
alex@mbaapply.com
www.mbaapply.com
http://mbaapply.blogspot.com