plz help me iam new to private servers

hello guys is there anyway to play here on wotlk fast ? i mean can we download something and start play on the wotlk server ? and the game data will be downloaded while playing in the game cuz i need that cuz it need much to download the 17gb so if we play and download the same way that gonna be much better . this method is activated on firestorm launcher and i try it its awesome but i need to play here so i need wotlk client they have cataclysm client but i need a wotlk server that make that ( DOWNLOAD WHILE PLAYING) thats awesome and thanks

The downloader thingy you're looking for does not exist for WOTLK.
Cataclysm and MoP yes, but not WOTLK.

can i download the cataclysm client then i delete
the cataclysm folders? plz help

You can find the Cataclysm installer Here

But if you want to play the WOTLK expansion, you really need the WOTLK client.

Cheers

can u give me mists of pandaria installer(download while playing) link?

It's here , there you go