It really depends on what "manage the business and deal with affairs" means. The level of the U.S. operations will drive much of the risk. As far as what structure, I would start with the idea that there should be a U.S. legal entity--the consultant definitely should not operate as a sole proprietor. Next, I would seek an accountant or tax attorney familiar with import/export to figure out how to minimize tax liability to the U.S. entity (which may determine the type of entity and ownership involved). Finally, I would work out a contract with the Chinese firm that defines the joint venture--keeping in mind that there are serious enforceability issues if the only assets of the Chinese firm are in China. The consultant should keep in mind that product liability and other serious risks could end up falling entirely on him or her if the Chinese firm has no other U.S. assets.
edit