2257 - since you say you want to use pics on your site, if they are non-nude or masked, then you'll be safe, But if you did want to use nude pics, you'll have to wait until the
current 2257 mess is sorted out before you know what you're supposed to do or not do as far as record keeping.
Warning page - it never hurts to use a warning page (we've been taught that it's "a good faith effort" to keep minors out) Plus it's another place to throw up a couple ads
