2
I don't use the contact us, but believe it use's the PHP send mail fucntion. and maybe effected by what you set in site preferences.
Preferences --> Mail setup
The E-mail is sent to the E-mail address set in your XOOPS admin
Preference --> General Settings
All above are in admin.
You may also like to try another module called Liase:
http://www.brandycoke.com/This allows you to create as many forms as you like, and define the elements within that form, so you can just use one form, customised to your or your clients liking.
Hope this helps.