not only need to install the IIS role but also the following IIS features:
asp.net, windows authentication, dynamic content compression, and IIS 6 management compatibility
source:
http://social.technet.microsoft.com/Forums/en-US/winserverwsus/thread/4e4756ea-136c-4272-9181-b7153904487e/

default update types to synchronize:
critical updates, definition updates, security updates

critical and security updates are default set for auto approval

1 synchronization per day default

installing wsus creates two local groups: wsus administrators, wsus reporters

wsus hardware requirements based off client capacity:
http://technet.microsoft.com/en-us/library/cc708483(v=ws.10).aspx
single CPU and 2GB of RAM seems reasonable for most environments.