Good questions, Dracula. The way the first three tabs work is:
Home: conversations are ranked according to things like freshness and activity. As the number of conversations on Cake increases, I think you'll see new conversations work their way up your home feed as they become popular, and then eventually appear far from the top on this tab as time marches on.
You can flip between For You (just the topics you follow) and All in the home tab, which will eventually become a firehose like YouTube's trending feed.
Star: Conversations you either chose to follow or posted in appear here no matter when they were started. Ones most recently modified float to the top, just like in a forum.
Explore: This is where you can navigate down a structure of sorts.
Does that help? Let me know if I didn't answer your questions.