Of course you are correct, but you are just pulling that price out of your a**. Since we're playing that game, the competition will also struggle if Apple can release a 4K display for $899, $799, or even $199.
I'm 100% certain the Phil simply flubbed his lines when he said "Firewire 2" instead of "Thunderbolt 2". And why would you want fewer Thunderbolt ports on a "Pro" machine? As for USB, I don't see any reason to add more of them. You can turn them into as many as you need with hubs.
Why do you have to wonder? Look it up..."Simultaneously supports full native resolution on the built-in display and up to a 30-inch display (2560 by 1600 pixels) on an external display." Reference, http://www.apple.com/imac/specs/
I don't understand. Do you want to plug a wifi adapter into your ethernet port so you can get 802.11ac? Apple released one of those adapters yesterday (http://www.apple.com/airport-extreme/). Set it on your desk and run an ethernet cable from the device to your computer.