1. Specify "listen=x.x.x.x" and add "children=N" directive as well
(e.g. children=5)
2. Could not resolve blah-blah comes from the fact that you do not
have a DNS reverse entry for this IP address. Try specifying the
following directives. They might help.
dns=no
rev_dns=no
Regards,
Andrey.
P.S. - This is just a warning, so dont worry too much. Nevertheless,
seeing warnings is not that pleasant anyway. I understand your
concern. ;-)