I'm quite new to this community, so apologies if I am suggesting something that already exists.
I like all of these ideas! Something I would very much like to see added is: A public and maintained list of safe and high-quality crates that can be used for security-critical operations. Here I am especially thinking of crates providing cryptographic functionality. This list would contain crates that have been "vetted" by this WG. I see this going hand-in-hand with:
Identifying common security-sensitive tasks and creating crates to provide the same functionality behind safe, well-vetted APIs.
So that there could be made a list of "When you need X, use Y.". Describing common tasks and recommending high-quality crates for those. For example: "Recommended multipurpose cryptographic library: ring".