Using AP to return to US seems not impact anything.
Using EAD working for the same employer will NOT affect anything. (????)
http://www.immigrationlinks.com/news/news301.htm
http://www.murthy.com/news/UDnewins.html
http://www.vkblaw.com/news/fivehundredtwentyfive.htm
http://shusterman.com/cronin51600.html
http://www.shusterman.com/h1memo500.html
http://www.shusterman.com/hl-99regs.html