Discoverability is something that could definitely use more work. Right now I recommend the site lemmyverse.net/communities, which is searchable and shows subscriber and active user counts. It should help you find where the most populated communities for your interests are located, if they already exist over here.

Your front page has three feeds. All is just what you'd expect. Local filters to only show posts from your home instance (lemmy.world in your case). I find it's mostly useful if you're registered to a smaller instance and want to keep up with local concerns.

Home shows updates for all communities you are subscribed to.