Affiliate Plugin- can every site use it or just admin?

I am just getting started and have lots of questions.

Can the affiliate plugin be used by all sites, or just by admin?

If all can, then this is one to be considered a "Premium" plugin.

Also, using this plugin, using paypal, on multiple domains/networks, not just multiple sites on ONE network, do you need seperate api info for every seperate domain? I noticed when I got mine for one site, it required the domain url, so I'm thinking api NEEDS to be different for each domain. Is this correct?

Tom