As part of broader improvements to auditing and STIG security compliance.
Yes, System > Audit shows the logs. TrueNAS records the shutdown reason, along with other details like the initiating user and timestamp. Ex:
No. If you manually submitted a debug as part of a bug report I presume it would be included along with your other logs, but there is no automatic collection.
Not currently. You could propose a Feature Request, but I don’t know how much traction adding an off switch to a security feature to avoid a minor inconvenience would get internally.