People, yes. Tags, not directly but if you follow kbin magazines most have related tags attached and you’ll get microblog content matching those tags in your feed.

Yes click on microblogs and you will see a ton of mastodon content. If you see someone ypu want to follow, you can.

Also if you’re in a mag that has selected tags the microblog section of that mag is just whatever is posted on mastodons under those tags.