Best network to buy adult traffic?

Hi,
Newbie when it comes to the adult industry – done my research but figured I'd ask here as well.

Goal: Get users to watch free porn videos (my site will not contain any ads)

1) What would be the best network to BUY adult traffic?
2) What type of advertising is the best for my goal – pop up, pop under, or banner ads?
3) What's the on-going CPM rate for your suggested ad type (above)?

Thank you.