I just installed CS3 Design Standard on my work machine today, and it was Illustrator 13, Photoshop 10, and InDesign 5, plus the smaller shared apps. The last version of Illustrator before the Creative Suite was I believe Illustrator 10. So yeah, CS1 was Illustrator 11, and CS2 was Illustrator 12.
No, I don’t think so. As someone who was “raised” on Illustrator 88 through 9.0, I find the CS versions somewhat frustrating because they changed the selection tool behavior away from something that is now burned into my brain and reflexes, but I don’t think there’s anything drastic between the recent few versions.