I don't think you need to get anything done from back home. We tried that because our daughter works in an attorney's office and it seemed easy. It was good enough the first year, but not after that. Every year they wanted more things done. The final word (as of a year ago) seemed to be get the original translated and notarized by the official folk (there are varying levels of these people; make sure you go to the correct one) in China. Take the original and the notarized translation to the American embassy and swear to them whatever they want you to say to get them to put the seal on a piece of paper that you can then give to the person getting your visa.
It took us three years to get it right. This year (our 4th doing things the spousal visa way) went off almost without a hitch. Ms. FAO had to produce our original marriage certificate and all of the above-mentioned notarizations and translations
again. (Why the same office doing the same procedure has to see everything again is beyond me, but who am I to argue with red tape?) I said almost without a hitch because the paperwork sat in someone's office for three weeks because that someone didn't know what to do with it. As the impending expiration date drew nigh and phone calls had proven unsatisfactory at producing movement, Ms. FAO went to that office where she
and insisted on seeing the boss. They told her the spousal visa couldn't be done.
(But there are three spousal visas in my hubby's passport AND they managed to do it last year.) Finally the truth - they didn't know how and didn't want to admit it. Ms. FAO refused to leave until they had called first Guangzhou and then Beijing to find out that they
could do it and
how to do it.
Expect problems. Work with your FAO. It won't all make sense, but it can be done.