We are a small company looking to start selling a card-game. The concept is known over the internet, where we've used parts of it but mostly invented the cards ourselves. However, we've used pictures that we're very unsure about whether or not they're copyright-protected. Many of them have been uploaded to the following website:

http://www.memestache.com/termsofuse

If you read their terms of use, paragraph 4 (if you didn't follow the link here's a copy):

"4. You hereby grant to us the non-exclusive, royalty-free, and irrevocable right to (a) adapt, edit and generally use and exploit all and/or any portion of the Content, alone and/or in combination with other content of any and all kinds whatsoever; (b) create and exploit derivative works of any and all kinds based on and/or embodying the Content; (c) distribute, publish, sell, display, store, exhibit, transmit, perform, broadcast, and generally exploit any and/or all of the foregoing; (d) use your name, image and likeness in connection with any and/or all of the foregoing; and (e) authorize others to do so. The foregoing rights may be exercised by us and/or our licensees, successors and assigns, throughout the world, in perpetuity, in any and all languages, and in any and all media now known or hereafter devised."

The problem here is that many of the pictures uploaded to this website have probably not been uploaded by the copyright owner, but rather by a random person who neglected these terms.

These pictures are used on a large number of websites, but due to the complicated bureaucracy very few people have used them for profit.

The obvious problem, which I highly doubt is even a question, is whether we'd risk a law-suit using these images or not.

I am quite sure we would risk a lawsuit from someone who'd claim to be the copyright owner and therefore my question is rather: how should we proceed to get the rights of these images? And if the answer here is personal contact with the copyright owner, which is absurd for many reasons, could someone theoretically sue us for more than our total profit we've made from this? The regions we're looking into are most countries in Europe, Canada and USA, but I'd assume there's an international law here?

Already Tried:
We've tried contacting a patent-company, asking their lawyer for advice. He did not give us the information we wanted. We've also tried looking all over the internet.