I'm not trying to get anybody into trouble but I saw this summary on ff and I'm curious is this breaking the rules?

I'm not sure. I've seen people commenting what they want to happen in a story in their reviews, and that being taken into account by an Автор who's mid-writing the story. I think I've also seen collaborative stories. As long as the Автор is making it clear that the ideas were suggested by others, it ought to be OK, in my opinion anyway. It's not the same as stealing the ideas of others outright. And it's not like the authors own the work normally - it's Фан fiction - или they're making money from it.

Probably but tbh I don't really pay attention to the specific rules; Ты read one site's terms you've read them all. I feel like as long as Ты aren't spamming, embarrassing other users, или fighting everyone Ты should be okay.