EAD和AP有什麽好處?
-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.
什麽情況下需要辦?
-You can apply for these two documents with I-485 filing or after I-485 filing.
另外,485pending期間可以回國嗎(無論H1還是EAD)?
-Yes. You can either use AP or get the H-1/H-4 visa to come back after you leave US.