1. It's owned by suse, not cncf. Only k3s was donated to cncf. At the moment it means very little, as we have not had anyone outside suse step up to help maintain k3s so both projects are maintained by the same team, and neither have required much action by way of governance. Note that distros do not have to be owned by cncf to be certified as compliant, in fact very few are.
2. Yes, you can disable the bits you don't like.
3. No, rancher has its own provisioning framework based on capi that it uses to provision nodes. That standalone capi provisioner is experimental and not currently used by any of our supported products. This is more of a rancher question than a rke2 question though.