I made a 16GB test card for CM10 last night, and it's pretty impressive. Chrome is super speedy. One issue I'm having that I haven't seen anyone else confirm is that sometimes CM10 doesn't notice when I change from portrait to landscape or vice versa, and it can take a good 10-12 seconds to rotate the screen. Other times it rotates just fine.
And um, yes CM10 comes with a file manager, but not a great one. I'd go ahead and install gapps along w/ CM10 and grab ES File Manager from Google Play.
One snag w/ setting up a card through Windows is that, unlike w/ the Nook Color cards you don't drop the ROM in /boot, but have to get it to the second partition somehow. If you've already set up ADB, the simplest way is probably to use the "adb push" command as verygreen describes.