EAD和AP有什么好处?
-EAD is for work, just like your H4 EAD, but I-485 absed EAD is free (no application fee). AP is used for travel to China (equal to visa), thus you d not need to get an H-4 visa to come back.
什么情况下需要办?
-You can apply for these two documents with I-485 filing or after I-485 filing.
另外,485pending期间可以回国吗(无论H1还是EAD)?
-Yes. You can either use AP or get the H-1/H-4 visa to come back after you leave US.