Is both petitioner and beneficiary notified when k1 is a approved?

You will receive more. Your fiance will not receive anything until the petition has been sent by the NVC to the embassy/consulate for visa issuance. Complete official details here: a href="http://travel.state.gov/visa/immigrants/types/types_2994.html" rel="nofollow"http://travel.state.gov/visa/immigrants/…/a