The permadeath thing is in reference to XP and possibly the complete loss of your inventory when you die. To be honest, this would have bothered me a couple of month ago, but when I was building my observation tower last month my game crashed while I was crouching over a ledge and when I logged back in I spawned at my bed. I was confused as I had never spawned at my bed before because I hadn't died since beds were introduced. In fact, I hadn't died in my SSP world in 7 months. Once you've established yourself in the world, dying should be very rare.
(Although, in saying that, I would have been pissed to lose all my XP because the game crashed while building a tall structure. I suppose it depends on how XP is implemented in the game.)
As for the hunger bar, it's part of a complete overhaul of the health system. Jeb didn't detail the new system but he did say that food will be stackable and it wont heal you instantly. I'm assuming that health will heal over time, like a slower version of peaceful mode, and how quickly you heal is related to how full your hunger bar is.