any docs required to be carried along while going for OFC appointment?

i have an appointment of OFC, for b1-b2 visa (tourist) on 1st of may 2013. iwhat are the documents required to be carried along? after this, another appointment is on 16th of may which , i guess, is for interview. i have been invited by my friend, to visit US, for tourism. i wish to know about possible questions. and what are the docs reqd at the time of interview. i am a central govt employee and have identification certificate fm employer giving details abt lengths of my service, my leave account, and my salary. will this help? plz guide me asap, on this and all related things. i am quite tensed. i intend to go for a month… should i carry a full file in original as well as xerox, of required docs? original for verification and xerox for submission??plz plz enlighten me with all required details abt b1-b2 visa…thnx

if some expert is open for chat, plz send me id for the same…