Does this require a SD card? Does CWM fully work without a SD card? Fully work as in, can it backup the system to the internal storage and such.
It does work without an SD card, but that's pretty dangerous. The reason being, is you have a much higher chance of wiping your files on your internal SD card, than on your external SD card.
There's only 1 way to wipe the external SD card, and that's to select "wipe SD card".
Your internal memory, if you wipe your /system or your /emmc or any other file system, you could end up corrupting your internal card, and causing issues later on.
To be honest, I haven't seen full confirmation that this will work without the ext-SD file system, but Hash stated that theoretically it should still work. I just wouldn't trust not having a back up on the ext-SD file system.