There's actually a thread dedicated to this soundbar, I just bought one too.
but to answer your question no you don't need HDMI, you can hook up your Cable box to the CT100 with the optical and you should be all set. Same with your DVD player.
The CT100 comes with 1 optical cord, so you may have to buy another for your other consols.
Or you could just hook up the Optical out from the TV to the CT100 and not do anything else and you're all set. It may not pass 5.1 though, we know it's doesn't pass 5.1 if your TV is connected to the cable box via HDMI but not sure on your set up. I would actually gives this route a shot and see what happens. If you don't get 5.1 then go back to plan A
Loads of info on this unit in it's thread.