Per-member prices for groups over 5 are discounted.
Yes! We have many group subscribers with as few as two members and as many as 200 (anything over 200 we will need to setup for you). Group subscription allows for many users to be managed within a single group and even a single payment. This makes organization and bookkeeping much easier. Also, you can choose to have up to three administrators on the account that have the ability to assign seats and make changes to the subscription. The administrator can be one of the subscribers with content access, or just an administrator with no content access.
Please see the full pricing information page here and let us know if you have any questions or concerns.