In short NO!! we have a facebook page but it is only for information about this site, we have no other interactions with facebook what so ever.
The facebook groups are very hard to sell on as your item normally disapears into the fog of all the other items, this is why I designed and made this site, to make it easy and friendly to sell and buy.
Credits are for the advanced features like additional pictures (you get one free), bring to top and featured ad, also some categories require credits before you can list in them. But a normal ad using none of these features do not require credits.