The little star shows those topics that you have posted in, so it isn't the same as subscribed topics. You can view all topics you have posted in by clicking on the "View your posts" link. You can't actually "unsubscribe" from them, except by deleting your posts, and there are limitations on doing that. And you can't add a star to a topic except by posting in it.
As you've found, you can bookmark a topic you're particularly interested in, by clicking on the "Bookmark topic" link at the bottom, and then you can find it again by going into your User control panel and clicking on "Manage bookmarks" down the left. You'll see a list of bookmarked topics, and can see whether any posts have been added to a topic by the colour of its circular topic icon. To go to the first unread message, you click on the little orange button at the beginning. See also here
. (Sorry if you already know all this, but it may be useful for other members reading this exchange).
As for un-bumping, I'm afraid that can't be done, so the topic will need to stay bumped!
Classical Guitar Forum.
"Experience is something you don't get until just after you need it." - Steven Wright