I get the concern but I don’t think you need to be as concerned as with email. Email is a lot simpler without a lot of validation. On the fediverse, HTTP Signatures are used to verify requests, so you can’t spoof stuff as easily.
That said, spam mitigation will probably still be an issue that continuously needs to be dealt with.
I mean… This isn’t inspiring great confidence. Fediverse platforms are by no means simple and neither are all the features you mention. I think you have good ideas, but as a professional software engineer with a masters in computer science who is also working on a fediverse platform… It’s not easy and learning everything from the bottom might be a big bite.