That seemed pretty quick. And apparently it's a minor update, code wise, so hopefully we'll see some action from the CY devs soon. Though, ICS probably has to hit release first.
The Cyanogenmod developers have been taking CM9 development a bit differently to the past, trying to make it less hacky, so it is both more stable and easier to port features. Since Jelly Bean is a minor update, a lot of parts should have the same, or a similar API. This means the CM developers can literally forward port and backward port features between ICS and Jelly Bean with ease. So they will be releasing ICS and JB releases simultaneously.
Yes. CM has rewritten their modifications for ICS so that they integrate side-by-side with the OS settings. If you didn't see the boot screen or the ROM version, you would just think that you got a whole bunch more features and nice little performance tweaks. They did an amazing job of keeping it stock and adding functionality where it made sense. All without the awkward, disorganized "CMParts" of CM(<9). It's all quite wonderful.
I'd rather CM sticks as close as possible to AOSP. Fewer potential issues for them in the future, and they get more time to port to more devices, and to make the "master" ROM more stable.