No I thinks is basically right although could be better worded maybe
/sys is virtual file structure for kernel system info
/proc is virtual file structure of kernel process info
My understanding is /proc came first but was abused/free for all and started being used for all sorts of non standard/process kernel access. So /sys was created with stricter rules to make it more standardised.
Nah, it's just that /proc is incorrect - it contains information about running processes, as well as kernel data structures as visible by the process reading them.