Yes, I am familiar with CIP-84, I reviewed it when submitting my own CIP candidate for a ledger change recently.
To be clear, I am not suggesting that we totally abandon CIPs for ledger changes. I think ledger changes can be documented as CIPs, I just think that the process for review/approval would be significantly different enough from non-ledger CIPs it may make sense to identify them separately.
In my ideal world, any change to the ledger would be covered by a CIP. In practice that may be hard to achieve, but I think we should strive to have hard fork change logs simply be a list of implemented CIPs (or whatever name we give a new process, if different enough).
Yes, please! I (as you know) am a big fan of the blueprint project and I believe we should really put a lot of effort into maintaining it as a central place for knowledge sharing.
That is an excellent question which I think will have constantly evolving answers. @arnaud has organized a poll to select a time for a first “Node Show and Tell” meeting where node maintainers can meet to discuss open-space style topics. I think this meeting is a great place to start to define a process for this kind of a process, as well as identifying other steps we can take to support node diversity. I hope anyone reading this that is passionate about node diversity attends!