What license are the images? There is a license mention on the bottom of the website but to me that seems to cover the website only, not the downloaded images. It would be great if each zip would include a proper license.
ShareAlike means they're unusable for commercial applications. I suppose you can still use them on a website, but I'm not sure how much of the website you'd also have to make CC-BY-SA.
No, ShareAlike means you have to distribute them under the same licence. Unless there is a NoCommercial, that doesn't mean you can't sell them, you just aren't allowed to change to a more restrictive licence. IANAL.
