1.For Xine player what all(rpm) should be downloaded-xine-ui,xine-lib and xine-skins??
Is xine-ui same as xine-fonts??
2.Regarding Mplayer I see many things like Mplayer,mencoder,etc...which should be again taken from net??
3.What about Amarok player?I installed amarok(in FC4) using rpm but when i tried to play mp3 files it asked for mp3 support/plugins..should i get those plugins from net??Can we see video files in amarok player??
4 At last in general let me ask about players available with FC4-helix,totem,CdAudio players,etc...do they have video/audio/mp3 plugins??
what is gstreamer used for??Can you tell me about these plugins needed or available??

You can find all this information by doing a simple google search. As for xine all i have is xinetd-2.3.13-4 and it works fine. Just mplayer and mplayer gui if you want it along with the codecs you can get from the mplayer web site. Amarok is a great media player as for playing videos i never tried i always use Mplayer but as far as the mp3 issue goes there isnt a redhat distro that comes with mp3 suppotr it has to be added I just removed the KDEMultimedia package and installed it again, I forget which one but it wasnt from the fedora repos thats for sure.

As far as all these go it's prob a good idea to look them up by your self, not every one uses them so just do some research it's painless and you should find all your answers on google.
EXAMPLE http://www.google.com/search?hl=en&q...=Google+Search