Is a link in the opposite direction allowable? i.e. can you add a link on your eBid store About Us page inviting visitors to contact you via Facebook?
Yes indeed, you can link to anything except an ecommerce site (your own or third-party like ebay). Oh, and porn possibly, but I don't think that one's been tested.
Yes yes, a balance is needed on Facebook. Your not allowed to spam the boards with continuous pimping (and I mean, like, every couple hours or so) I pimp about once a day.