@PerkFGC @cgquarterly @britt a) Make sure you click through to see their account on their (remote) server. Your local server will only have info on them that it knows about, so for instance, someone may have 50 posts made, but if the server has only seen 3, you will only see 3 until you click through to view their account on the remote server. Then you will see all 50 posts, their followers, etc... Usually, there's a link or something on the profile to say "click here to view their full profile on the remote server" or something along those lines.
I have not tried this yet, but there's an extension that you can use that eliminates this extra step as far as I am aware. You can check that out here:
https://mastodon.social/@mmasnick/109532913088221650b) Some instances allow users to decide to hide followers/followed as well as the actual number of followers/followed too. I'm not using Mastodon right now but a server named Akkoma which does allow those options (but I don't use them, personally).
c) You should be able to find and follow anyone on any other server with the exception of servers that your server may have blocked (defederation/fediblock), but that would be usually in rare cases.
Let me know if you need more help, it's no problem.