I can guarentee you the PS4 will support 802.11n, and the 5GHz band. Not doing so would not make the slightest bit of sense, it supports USB 3 and USB 3 is way newer than 802.11n. Are you refering to 802.11ac? ac is way to expensive right now, and it's still fairly new to consumers. I understand their decision, and n is perfectly sufficient, if you hate the speeds and your router is a mile away than just run a 30ft patch cable.
The PS4, Xbox One and Wii U have disk drives, this won't happen for another few years. This may never happen because people like to have physical copies and so do collectors, and there is definatly a market for that.
I don't have a PS3, but I pre-ordered the PS4, I am hoping they do let us play PS3 games on the PS4. (even if it has to be digital, through PSN/gaikai) I just really want to be able to play The Last of Us, the God of War games, Injustice Gods among us and many others that I missed out on, I would buy these titles in a heart beat on PS4. I would buy a PS3, but I spent enough money on a PC and pre-ordering PS4 as it is. Here's to hoping I can play the PS3 titles I missed out on.