I think I can help on some,
Number 1 is from a series of videos, made in Japan. I have a clip somewhere where about 50 naked girls compete in sports events and even have a 'pissing from 25ft scaffolding, into a jar held by another naked girl' competition, oh those japanese are whacky!!!
Number 2..... comes from a Hollywood film, the woman highlighted is quite famous (the others are also big stars) but the film and stars escape me! It's a 'girly' film about female bonding type stuff!
It may be this one?
http://www.reelviews.net/movies/l/live_nude.html
Number 3
This is from a 2008 UK touring production of Equus, the guy (Alfie) is the son of UK oddball celeb Keith Allen and brother of pop singer and TV host Lilly Allen. He is (after seeing a video doing the rounds this week from the US production), a bigger boy than 'Harry Potter'
Having looked at those pics, the one on the right is (I think) photoshopped. I have a censored version (released to the UK press) and his penis looks very different to the one on the left, which I think is genuine. Maybe 'Harry' can breath easily now
http://www.equustheplay.com/home/
Number4 is from a 'commercial' Tunick shoot, called something like 'The picnic!' I think it was shot in New York, for a magazine. I have seen the shots in Time Out magazine in the UK about a year ago.