Sheriff: If you're uncertain, refrain from posting it. Copyright (and other intellectual property) infringement threatens the forum as a whole (due to vagaries of U.S. law that I'm not going to get into).
Similarly, we're not going to give you legal advice about whether your fan fiction, derivative work, or whatever violates the law. Nor should you seek such advice on this forum. If you're not sure you have the rights to everything in the post, don't post it.
That said, the rules states:
It's broad because we want it to capture a broad range of conduct. We want people to use the default rule of erring on the side of caution.Posting Copyrighted Content
Posting any copyrighted material without permission of the copyright holder is against the rules. Likewise, please do not link to copyrighted material being hosted elsewhere without the rights-holder's permission. Posts containing such content will be edited to remove that content.
Also, notice that this prohibits linking on the same terms as posting. So if something is hosted elsewhere without the right to do so, don't link there.
Generally, what this means is that you can talk about a thing, but you can't post the thing here or link to the thing posted elsewhere without license/permission. The best course of action is to describe the thing in your own words or point the reader to the legitimate source and let them find it lawfully on their own.
What about "fair use," one might ask? That's another legal concept that we aren't going to apply for you here, nor should you seek advice about it on this forum. What I will say is that fair use exists, it's a muddy area of law, and we're not required to accept or enforce it to its outermost limits. Fair use is much, much narrower than most people think, and it doesn't make something acceptable just because it's small or not-for-profit or credit was given or it was changed it a little from the original.
Regarding your specific examples, you should ask whether the place you are linking to is doing so in compliance with copyright law and for whatever you post (text, image, link) do you have the right to post that material. If you're at all uncertain, just don't post it. Try, as much as possible, to assume your reader has the source material or will obtain it legally to engage in the discussion.
That's about as much official interpretive help as I can give you. It should be enough, even if it isn't all that was desired.
EDIT: Originally, this was all posted in red text, but it was really rough on the eyes to read that much red text.