i dont realy think its a question of how many you can make it will only become an issue when you start receiving a lot of traffic
you dont sell your host name you sell the domain and site you could transfer the website to the buyers host or give them your login to download themselves
adult pay per click i dont know of any
if you want to buy adult advertising or sell traffic use
juicyads.com
and i find
xprofiles.com
has a realy good payout of $1 per free sign up
hope this helps