Hello,
Vendors can set-up a "terms & condition" in their profile (depending the ACL you configured).
It is also possible to add new vendor custom fields to let them have more than just the "terms & conditions".
It requires some configuration and a view override if you want to have a special display for these elements.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.