Unless the TOS has changed from DSL I've been able to run server and even allowed to run a mail server on my residential DSL and now U-verse account.
I'm not sure about static IPs especially for business but I can tell you as long as I've had my service (almost 2 months) I have the same Ip address since install and the Remote gateway has been unplugged many times. I'm pretty sure that if you are paying for a business account you'd have booth abilities.
