The good thing about Fediverse is the decentralization.
There's no one Lemmy instance, or Mastodon instance. You could use any server, or even selfhost your own, if you wanted to, and have pretty much the same potential for reach.
That's all anyone needs to know about the Fediverse.
The hard thing is authenticity. Particularly for public figures, celebrities, social media personalities, businesses, etc. People who want or need an online personality that corresponds to their real one. I really don't know what the method is for "proving" yourself on the Fediverse.
Depends on a few things. Instance admin can rate limit requests. Pretty easy to identify a bot that's scraping traffic.
That's also one thing I try not to worry about. I don't generally say anything online I wouldn't feel comfortable saying on a soapbox in town square (generalized anxiety disorder aside). As a nerdy 90s kid, I learned anything you put on the public internet is public domain unless stated otherwise, and will probably exist forever (if only I could remember any of my GeoCities addresses).