Verified answer

I believe it depends on what kind of copyright has been placed on these images. Are they stock or from a professional portfolio? If they're stock than there should be some sort of statement as to how and when they can be used. If in doubt, try contacting the photographer and asking them about it, if they've got contact information up.

You should be looking for a creative commons license (I think that's what it's called) or a statement as to how the stock is to be used on the page the image you're using is posted. If there's nothing of the sort, resort to talking to the photographer/artist if you can find contact information that they've posted, or find a lawyer and ask them what the laws regarding such uses are.

It could if you're selling these; which surely you aren't. One "rule of thumb" my favorite Graphic Arts professor told his students is that if we are inspired by someone else's design; that's one thing. If you want to make a design fully your own (though you've been inspired by someone else's art work)--you need to change at least 3 major design elements. Hey, best not take my word for this, though. I'm no professional anything. I am aware of the fact that there are "Lawyers for the Arts" groups throughout the USA, at least. Some of whom will give some of their time "pro bono" (free). I'd think that you could get a more definitive answer to your question by asking an attorney who offers some sort of free consultation. Hope this helps.