When you report a post/comment in Facebook, it does it via ajax. Then the reported item is hidden and says that you reported it.
So this is really a feature request and theme change. The feature would be to add a post to your ignored list and give you the option, when reporting a post, to ignore a user altogether.
Umm, not sure about this. Just because you report something, it doesn't necessarily follow that you want it ignored. An example that springs to mind is when a forum member expresses a desire to self harm. In that case you probably want the staff to know about it, and probably want to keep an eye on it yourself.
From what you're saying, it seems Farcebook (which I never use anyway) will automatically hide anything you report.
A report can also be a helpful hint to mods that a topic is in the wrong section, or parts should be split. There's a good reason someone might want to report a post and continue to see it in order to reply in that situation.
When you report it, it can ask you if you want to ignore it. When you ignore it, it will show a small bar "this post has been ignored [unignore] [hide all posts from this user]". No changes on the backend (other than grabbing the posts that you ignored), just on the frontend.
"Unignore" is not a word. :P