You're a Workplace Admin for a major retail chain in Europe on the Slack Pro...

Yes, because Slack's disaster recovery policy and business continuity plan provide backups that organizations on the Slack Pro plan can access upon request from Org Admins.

Yes, because Slack employs multi-factor authentication for all administrative access to systems. Slack can access channel history upon request from Org Admins.

No, because this company is in a territory affected by GDPR. Slack is legally not allowed to provide this data after the retention date has passed.

No, because customer data is removed immediately upon expiration of message retention. Slack deletes all information from production systems at that time.