You really don't need to root unless you feel the need to run ROM's.
If you do root, wait until you have updated. My advise is to also only used officially released OS's as well. The leaked versions don't have the final tweaks the official build does and you generally only have to wait a couple weeks to get the official version while everyone else runs the leaked version.
I also suggest you flash your phone back to stock before installing a new official version over an OS you have used for a while. YES, you will have to reinstall all your favorite apps and settings. However, your phone will run MUCH better as a result. This is no different than reformatting your computer hard drive before installing a new OS.