@watchfulwheel there's three timelines, Home, Local, and Federated (see: https://social.privacytools.io/@jonah/101825503333455540 for what goes on which ones).

If you use hashtags in your posts they'll be more easily discoverable in search. 500 character limit on posts.

You can follow people on other instances, usernames use the format "@jonah" (like email) where "@jonah" is the username and "@triplebit.net" is their instance. If you want to share your profile on other instances you need to give others the entire thing.

@watchfulwheel I read this guide before opening an account. It explains it pretty well.

https://kevq.uk/how-does-mastodon-work/