I think all you need is the AppleTV and the screen ... what would you need the Ethernet hub for?
I'm pretty sure other bands are doing this, but I haven't tried it myself, so hopefully someone with first-hand experience will chime in here.
If you want to add more screens, the HDMI splitter is a good idea because currently you can't mirror to multiple AppleTVs.
If you want to save a little more and don't mind another cable on stage, you could also attach an HDMI adapter to the iPad and run a cable to the screen. But the HDMI adapter costs half as much as the AppleTV!