I'm glad you're enjoying the forums! I would ask you to start creating new threads for any further questions, if you could. Sometimes it's harder to tell if a new question is being asked, or if it's follow-up conversation. I'm going to put your new question into its own thread now, so no worries: It will get answered. :-)
Also: All the cards from an expansion have an expansion icon. So, Munchkin 2, Munchkin 3 and so on, all have their own icon, found on the bottom center of the card, to indicate what set they come from. If you go to the web page of an expansion, you'll see the designated icon for that set on the left side, underneath the cover art. I'll provide a link to
Munchkin 2 so you can see what I'm talking about.