3-
No minimum posts per week
That's actually a good thing, I wish more signature ad campaign had no minimum quotas of posts per week, people shouldn't be incentivized to make useless posts or risk getting booted out of a campaign.
Although a maximum amount of post should be set to prevent spamming of the forum without limits and it should be a reasonable amount like let say maximum of 7-10 post per day i.e maximum of 50-70/week is somehow appropriate.