You use boosts as a thread to as a save function. You can view your boosts in your profile. As for hiding, you can block a magazine to hide that specific magazine in your feed, or you can block a user to hide their posts.
There currently isn't any way to DM someone privately. You could chat with them in the microblog, then delete it when your done. Otherwise, ask then to chat in another chat platform, like discord.
Ernest is trying to automate the process of replacing inactive mods. It's unclear to what will happen next after he's done. Keep in mind that other instances are also having this problem too.
Unless your encouraging users to harass other users, you can add any rule you want. It might be hard to do that idea you mentioned since you can't prevent users from posting content, even if it's a part of your rules.