I really empathize with the feeling of being overwhelmed with all the settings at first.
Something I’d caution against is letting perfect be the enemy of the good - there is no perfect setup, things are going to need to be tweaked over time as your community settles in. It’ll always be a little bit in flux. It’s also very likely that much of the time spent designing a setup can be thrown out the window once it goes live and users start throwing feedback your way (I’ve learned this the hard way!).
Something that’s helped our community is to have a group of beta testers. They have their own group, they have their own category, and there’s a specific theme for testing components. They’ve provided a lot of great feedback over the years, and can spot potential pitfalls or things I hadn’t thought of.
I think just getting started with a minimum viable product will help immensely. As you get feedback from users, you can adjust as needed, adding or removing plugins/components or adding/removing categories, etc. You don’t have to have a fully fledged out category tree right away, you can learn over time what works. If you’re nervous, bring over some users before fully launching to get their feet wet and get their feedback - having users familiar with discourse will help in the transition as well.
This all allows your community to help dictate the feel of your discourse instance, giving them a say in the matter, which enables them to feel more connected to it.