Is it the same here in newbie? I mean, I'll also just post things into bounty just like what I am doing now right?
Almost signature bounty campaigns require minimum Jr. rank. If they are a professional bounty manager, they always ask you post/reply in main boards, (which in off-topic are not counted). Sometimes, they ask for the minimum characters and contructive post/reply, trash/nonsense will not counted.
Maybe there are more rules, you have to read carefuly before joining a campaign.