RealPlayer, Mplayer, Movies and Question about RPMS

[Benjamin Sher]

Dear friends:

I am new to Fedora. Just installed Fedora Core 6. Very pleased. Two or three 
quick questions:

1) If I install RPMS from outside Fedora's repositories, can Fedora 
incorporate this installation into its database? Or is it enough just to make 
sure that the rpm is a RH or Fedora rpm?

2) Where do I find the rpms for Mplayer. I would like to then use 
mplayerplug-in with Mplayer.

3) Where do I find the appropriate libdvdcss for playing movies?

Thank you so much.

Benjamin