Wow, well done on building such a healthy community and thanks for choosing Discourse for its new home.
I think you’re heading in the right direction, thinking about the needs of the different personas that make up your membership. It’s hard for me to comment specifically on your architecture because I don’t really know your community so I’ll give you some general advice, which may or may not be useful.
Start small, with the minimum number of categories possible because the paradox of choice is particularly present for people that are used to the social media model of consuming content. You can always add new categories as friction starts to appear, but if people are confronted with too many decisions they’ll become frustrated.
I think your documentation pinned in each area is a good approach for this community.
Tags are a powerful tool – see my more detailed thoughts at It’s Time We Talked About Tags. But… I would be wary of introducing them to an audience that is used to Facebook.
I see where you’re going with this but I’d be careful about restricting people from being able to share in a grief category. It may be more upsetting than helpful, esp for a community of non-technical users.