EAD vs H1 with pending I-485

[dramakr]

I guess due to priority date movement a lot of people may be in similar situation. I have my EAD card approved as of Mar 2012 and have H1 extension (requires stamping if travel abroad).

1. For travel, is it better to use AP or try getting the H1 stamping? Will it invalidate the H1 if I use the AP

2. I am planning to look for new opportunities but is it OK to switch employers at this stage. My PD is March 2009 and sure the wait will be longer for GC approval.