You accept newbies on this campaign but you have a requirement "Your bitcointalk.org account has to be at least 4 months old" ? 4 months old bitcointalk account should be a member rank almost to full member (in case the account is active posting)
Regarding the rate, yours are good especially for "newbies" but 20 max posts per week is a bit low imo. Would you consider to increase the max post count or maybe just make this campaign as a fixed campaign.
Makes no sense does it?
If you are a newbie that posts 20 good posts per week you are not a newbie after 4 months, but full member (120+ activity).
If the rule stays people will probably just buy old newbie accounts for cheap to join. Probably not the kind of people you want advertising for you.