Vlad,
JFBConnect, like every other extension, is not perfect for every site. It's possible that maybe you don't need the features of JFBConnect.
To answer your questions though, yes, a user does not have to login to your site to post a comment using Facebook. You can use ShareThis, or other tools, to add social buttons. However, JFBConnect does a lot more than just the things you mention that other tools or manually adding the tags do not.
When a comment is posted to the user's Facebook wall, Facebook uses the Open Graph tags from your site to describe the page to the user's friends. JFBConnect lets you set these tags easily. ShareThis also doesn't know or understand the structure of Joomla's URLs. So, if you use their addon, your Like counts will be spread across multiple different URLs.. non-SEF, SEF, ones with a ItemId (from a menu) and other URLs that are generated for the same content. JFBConnect, again, knows how Joomla URLs are created and creates a canonical URL for most content so that even if 2 user's visit the same page through 2 different URLs, the Like button is the same for both.
As for the actions you're talking about, that was discussed in the post below. The next release *will* have actions that can be automatically inserted into the user's Facebook timeline. We will have support for jReviews, so different types of actions on your site can be posted to your user's Timeline, which is great for promotion. Our system is going to be very flexible so that you can easily create new action types like you're looking for:
www.sourcecoast.com/forums/jfbconnect/jf...book-wall?p=1#p27479
Finally, there are a huge amount of other features in JFBConnect like Friend Invitations (Requests) that user's can send their friends, Facebook Page Tab integration, profile import ability, 1-click registration, and many, many more things. While you may not want or need all of those features, they are things you may grow into with time as your site grows and you need to enhance your social promotions.
Again, it may not be for you, but putting together a lot of separate tools to do everything JFBConnect does is very difficult (if not impossible) and much more prone to mistakes or errors.
Hope that helps,
Alex