Bartosz,
For the social buttons, both should show at top and bottom. Can you tell me what kind of view that is in K2? Is that just a standard article, a blog view, or something else? Looks like an article, but blog views with one article can look similar. Also, can you tell me if you're showing intro text or not there? That will help try to recreate the problem.
For the 2nd question, yeah, CSS is the best way to do that. Simply adding the following to any CSS file that is loaded (usually, there is a specific template CSS file for custom tags) should do it:
.jfbccomments { margin-top: 10px; }
Hope that helps, and good luck,
Alex