Help on job appointment letters

Hi, FriendS:
What kinds of paperwork I need? I have three years H1B from 2005-2008.However, my contract with my current boss will end Jan 10 of 2006.My boss will continue to hire me for next year.So under this situation, should I get whole hiring paperwork including human resource appointment letter, department appointment letter et al? Do I need these documents if I go to visit my parents in China?Your suggestions will be greatly appreciated!
Thansk!
Lily