They see the destinations of those packets, so they know what sites (IP addresses) you're interacting with, on what ports.

They don't get the domain names, but for the very popular web properties that all these analytics care about calculating your relationship to, they don't need them; the IP is enough to discern which site you're visiting.

Yes, and the IP addresses there are public, and reverse DNS entries are easy to find. There's some ambiguity, but not much. Your isp doesn't care about the difference between fbcdn.net and Facebook.com when selling your traffic history.