Dates can indeed be formatted.
For labels, as far as I know there is no way to control them separately. There are three options: keep them all, all the time; hide them all; and make them appear when the node is created, and fade later. This last option will make also appear the labels of the parent nodes, including the categories.
Unfortunately, at this scale and speed (1 day => 0.05 seconds) the third option still looks super messy. If you are visualizing one category (~ 2,000 posts, 1 day = 0.1 seconds) it is doable, though some of the paths looks really ugly (catname/subcatname/1234/5/6/7/8/9/10/11 or so).
Any feedback on the Edgeryders stories we could tell with these data? (“Hey, I can see when @johncoate started his monster “Status report” topic!” and similar)