Zotero does have an item/format type for artwork that includes a number of fields, including IP rights. This works with sites like Flickr, whcih will also automatically capture a screenshot with the image (depending on your Zotero preferenec settings) .
You may need to change your item type from Web Page to artwork (or perhaps have one of each, to account for different ways of citing). The Artwork format will provide better bibliographic elements for the actual work.
As with other bibliographic references, if you use an image and need to cite it, if it is in your Zotero library you can either drag'n'drop in your appropriate citation style, or use the Word/Libre Office plugin to insert the image citation in your document.
To capture just the image, you can either download the image and upload it to Zotero as an attached file. You can't insert an image in a Zotero note, or at least you can't if you are going to try to sync it to Zotero.org.
1/4/18 update: According to Zotero, "Notes with embedded images cannot currently be synced to zotero.org."
How to insert an image in a Zotero Note (works with Firefox and Chrome; I have not tested it in Safari)
Zotero and Flickr
Flickr has its own translator, but although that captures OK metadata, it only captures the image, not the page. Be sure to use the paperclip to also attach a screenshot of the Flickr page itself, to preserve info on rights, geodata, etc. (you can add that info to the item's Zotero record fields as well).
Don't forget you can use Zotero to make citing images that you use in presentation software easier! To get a standalone URL for Flickr, click on Share, then on the Grab the HTML/BBCode link and select the .jpg URL from the code.
Pinterest is Open URL-compliant and has a browser translator/icon that will download the Pinterest item you are looking at as a webpage; alternatively you could save it as a webpage. Both methods capture different elements, and neither is comprehensive. I think I'd give the preference to saving it as a webpage, but you will need to carefully add in bibliographic details - which adds to the complexity (author field options are author, contributor, translator -- collector is noticeably missing!)... [more later - I need to fiddle with Pinterest a bit more - if you have ideas, please comment!]