1) Unless you are an attorney, you cannot represent your husband in arbitration; arbitration is considered equivalent to a court proceeding for this purpose, and only a licensed attorney can represent another person. Your husband could represent himself; you may not represent him.2) Whether your husband can get his employee file depends on what any arbiration agreement or clause in a contract (like an employment or union contrat) says, and also on the rules under which this arbitration is being conducted (there are several different arbitration rules, which  are not the same); there is no one-size-fits-all answer to this part of your question.