Tourist VISA for USA Passport holder in Hong Kong or Dubai

I lived in Tanggu three years with a multi-entry Work Z and Permit. It is now expired. I work in Iraq and would like to stop off in China for visit and vacation for a couple weeks in April and first of May 2014. Getting a letter invitation from China is no problem. I am American from Louisiana my USA passport is good to year 2021. Could I possible apply for it in Dubai or on arrivial in Hong Kong without returning to USA first. If so how long would it take. I am presently in Iraq working and would like to stop over in China Tanngu and Beijing for a visit with old friends on my days off and possibly visit Qingdae would be my plan for trip.