How to using ultimate facebook from multisite?

Hello my friends,

I come again..=)

I've already setup multisite in my wordpress site.

So, I Install Ultimate facebook at my network admin and WPMU dashboard.

My questions are :

1. How can I install ultimate facebook to my client's site from my multisite wordpress admin?

2. I've install the ultimate facebook on my multisite using my Facebook Api Key/secret and of course if I make any post, it will post automatically to my facebook wall but how should I change user from my multisite using their facebook API key/secret ?

3. Am I need to install the plugin at the user's site? If I install the plugin at the user site, it will show the notifications from WPMU for any update at client's site. I don't want the user know about this. I just want to setup from my multisite and when user make any post from their blog, it will automatically post to their facebook wall and I'll control it from my multisite admin.

Please help me to solve this problem.

Thank you for your cooperation.