It certainly sounds like what you’re trying to do, but I can often be wrong. 
If that doesn’t work for you there is an open feature request for multiple topic drafts here you could add your use case to - Allow multiple ‘new topic’ drafts
Just as an FYI, we try and keep one feature request per topic so we can track them better, so you may need to pare this one down. 
For hidden posts, do you mean hidden topics? There is the Unlist feature that would make them only visible in the topic list to admin, mods, TL4 - though they’d still be accessible via a direct link (and send out a notification to anyone Watching/Watching First Post the category). You can access it from the gear menu in the composer when you create a topic. Though normally we would recommend creating a shared draft, or simply creating the topic in a permission-controlled category and recategorising it somewhere more public when ready.
And in case it’s useful/relevant, you can have multiple post drafts, but only one per topic.