Hi @crspybits you might be interested to know I’ve been looking closely at your point b) for a while 
m-ld is a tech for live-sharing an RDF graph, using CRDTs. I’ve been chatting to various people in the Solid community about it over the last year, with the intention to interest folks in integrating it with Solid. There’s a discussion of the technical details on m-ld’s discussion board here: Integration with solid-community-server · m-ld · Discussion #71 · GitHub.
With regard to point c) there are quite a few scattered mentions of this in the Solid ecosystem. I gathered them up when I was putting together an NGI proposal last year, which you can read here: Integration with the Solid Project · Issue #62 · m-ld/m-ld-spec · GitHub