The little number in the circle is your reputation score. This essentially lets other users know how much of a contribution you've made to the community, how many followers you have, how active your posts are, etc. It's a ranking system. The more engaged you are, and the more people engage with you, the higher your score, and in general terms the greater return you can expect from your posts.

As for @cheetah, it is a fraud detection bot. I'm not quite sure how it works yet, since I haven't had a run-in with it, but I've seen others use the !whitesheet command (I think) on behalf of the users being questioned.

As far as your blog and posts are concerned, your blog is a collection of your generated content. Any stories you submit will be displayed under your Blog. The Posts tab, on the other hand, includes both your blog posts and any replies or comments you've posted as well.

For your users on Facebook, direct them to the entire link (https://steemit.com/@yourusername). That will take them to your account page, where they can see your posts and blog, and where they can find the Follow button in the upper right hand corner.

Hope that helps. :) Welcome to Steemit!