If you follow a Hubber, you'll get announcements of all Hubs created by that person. But once you visit a specific Hub, you can choose to post or not, and can "unfollow" that specific Hub at any time. Once you unfollow a specific Hub, no further post notifications from that Hub will come to you. You'll also get no post notifications if you never post to the Hub (in this case you'll just get the original Hub creation announcement).
You can bookmark a Hub by right clicking on the page, and choosing "Add To Favorites." A link to the URL will be in your MSIE Favorites dropdown. This will not in and of itself result in any emails being sent to you.