There are all sorts of discussions in the obsidian community about the architecture/metaphors of note organization. Zettelkasten is a popular one. I would recommend reading about them and coming up with a paradigm that suits the way you think. You can read more about it here.

Yep. Unfortunately, Graphene requires further investment in google products. Buy used/refurbished! Or go with Lineage.

Graphene OS is working well for me and installation was pretty straightforward. As people have said, though, it needs access to the bootloader.

Nice. Perfect game for Halloween!