How To Root With Official 2.1 Installed

[blackrain]

I was wondering how do I install rooted 2.1 with the official 2.1 installed already on my device?

Also what will i lose/gain with dropping the official 2.1

Will I still be able to install my same apps i have some .apk's that i would like to keep ringo pro etc....

Will I still be able to install things from the market I believe I read somewhere that you lose the ability to install certain things from the market.

Last thing would be which is the best rom also i read something about a kernel so also which one should i install for that also.

Please take it easy I'm fairly new to android I just deactivated my tp2 for a little while to give android a fair shake so I'm walking into this thing with both eyes shut!