The traditional word for "转载" is "reprint". For example, magazines might have an article "reprinted by permission". "reprint" might sound slightly odd for websites, but I think it's still the best word. You could also use "copy". Informally, people also use "lift" in the sense of copying. All these apply to printing or displaying the content, not html-linking to a source page. Linking is not reprinting. These words don't seem to be used that much though, because copyrighted contents are not supposed to be freely reprinted, and when there is a special arrangement that allows it, they might have a special name for it, like twitter's retweeting, YouTube's video linking, Google Reads, etc.

It depends on the site as well as the material. I think "post" or "link" (or even "post a link") might the best answers. If you're using Twitter, it would be "re-tweet."