1) Good idea but it should be restricted to certain sections only.
2) I prefer to offer 2 alternatives :
First one : ICO don't pay anything but the manager has to open a self-moderated topic and like the wall observer topic, all reports go to the manager and he is obliged to remove the spam or else the topic will get trashed.
Second option : ICOs have to pay a fee that goes to the forum mods to clean the spam out of the forums.