Styx online

How long am I suppose to keep someone's resume on file? How long am I suppose to keep old employee files? How long am I suppose to keep work that pertained to a client but I am no longer working with them? Is there a Documentum Document Management program or company that I can hire that can come in and clean up our old files and tell us what we can purge and what information we legally have to keep on hand and for how many years? I am getting frustrated with all this storage that I need for information that does not deal with our business today.