An easier way to follow is to paste any of these urls into the mastadon search box, and then click on + button next to the account. This avoids needing to fill in your account details on the remote site.
If I were to setup my own instance, like you, how do I interact (read & write) with other, curated instances (e.g. octodon.social, mastodon.social etc.)?
Remote follow enough specific people you are interested in and some of the rest of the instance's traffic will show up in your instance's Federated Feed as it interests them.
Sometimes if the remote instance's entire feed is interesting I might set up a "read only" account on that instance to get an idea of people to remote follow from my main account. I've heard good multi-instance clients can help a lot with that, but I've not yet found a multi-instance supporting client I like.
Okay, yeah, doesn't seem to be too many out there. So no real way to do this now, except what you described. You can follow specific people, but no local timelines of instances.
Yeah, there are also interesting experiments out there, like some instances run bots to try to "collect them all" and follow almost everyone they can in the fediverse. The one that found my instance first was @federationbot@mastodon.host.
It's not something I've considered on my instance, to keep costs down and because I like the opportunity to curate it manually a bit.
@eevee@mastodon.social was surprised by all the people suddenly following them... As they've tooted, a lot of what they post could definitely be seen as not safe for work.
https://mastodon.social/@eevee - good tech blogger
https://mastodon.art/@Curator - admin of an art-based instance who boosts lots of cool art
https://framapiaf.org/@davidrevoy - artist behind https://peppercarrot.com
https://octodon.social/@emersion - friend of mine who works on cool projects with me
Orgs
https://mastodon.xyz/@Liberapay
https://mastodon.art/@Krita
https://mastodon.technology/@kde
Bots
https://apoil.org/@NextLaunch
https://apoil.org/@nasa
https://apoil.org/@ESA
Me
https://cmpwn.com/@sir
How to follow -> click "remote follow" on any profile and fill in your account details.