You can look up the actors in a movie or to get a review of an actor's or actress' career using the All Movie Guide (free), the Baseline database on Lexis (ENTERT;TITLES) or Magill's Survey of Cinema, which is available through Dialog (File 299) and Westlaw (MAGILLS). Or just put the actor's or actress' name into a good search engine and see what comes up.
To find out who represents a movie actor or actress, call the Screen Actor's Guild's "Representation Line" (323-549-6737 or 323-954-1600). They'll give you the agent's name and phone number. Alternatively, you can can look up this information in the Academy Players Directory. Subscribers can search an online version of the Directory (www.acadpd.org/index.html).