Here's how question work. You request opinions on a topic in your posts, people give their opinions in the comments. Loading a question with your own opinion will disqualify it from being a question. Loading a question with media or other links that answer it disqualifies it from being a question. Posting an opinion and asking what people's thoughts are on it is still an opinion. Rhetorical questions are considered statements.
A link to an article with a question mark in the title and a copy of the article's title as the post title does not constitute a question, it constitutes promotion. A post containing a "wow guys, I found this link, what do you think?" is also promotion. In general, any post that is more a reference to outside material than a user's own question is likely promotion.
If you want to shitpost, be creative, be original, at the very least be entertaining. Make juicy content happen, and you're part of the community. Keep making people cringe, and you're just a clown, and a bad one at your job. There's no hard rule for this, but getting banned for a long time just for shitposting is unlikely.
A megathread will be stickied to the front page if there's a lot of content on the sub on a single topic. Sometimes it might be a post with a list of megathreads. Sometimes there might not be one. Contain the megathread topic to it and don't give us too much work cleaning up the rest of the board.
The Megathread is designed for a specific topic, with its own set of rules that may or may not differ from the rules of the larger community. The Megathread is not a lawless free-for-all. Posts that are not relevant to the topic of the thread will be removed.