I have been to both Whitney and Mt Russell in October and November. The rivers start freezing over, the days are shorter, and nights are quite cold. But if you are lucky, and there has not been a big storm yet, most of the route will still be dry. There is Ice on some of the chute above the Notch, which is no different then most of the summer.
Average temperatures in town in October are reported as 76/37. That means 53/14 at Lower Boy Scout Lake and 45/6 at Iceberg lake.
Doug Sr's Mountain Lore at the Whitney portal store has a good description. Lots of good pictures of the MR on this site also. Snow Nymph was just there
http://community.webshots.com/album/173208815vwdvsA/0Bob R' has good photos of the EB ledges and the chute above the notch. See
http://members12.clubphoto.com/robert634908/943486/guest.phtml