The real mystery here is how nobody noticed that "active" timestamp has pretty much always only appeared on questions with at least one answer. :)
The original version of the sidebar back in 2008 included more stats about the answers, and that information was hidden for questions without any. Looks like over time, that gradually changed over to just hiding ...
What "hot network questions"? On the sites where I have accounts? All sites? My favourite sites (defined somehow, I might be very active in some sites, and just occasionally peek at others)?
If not filtered somehow, this gets to be just so much extra spam.