Someone may have cloned his sim card on his phone. He needs to talk to his banks not you. Change account numbers. Someone, like a close relative that he doesn’t suspect has access to his accounts.
Yes, but he does later mention moving to Exchange. And as I said there is no reason to change to M365 if you already own Office. Most people have the stand-alone to avoid monthly fees for what is for most people a static program.
I'm sure she is referring to upgrading the client to the email provided by Microsoft 365. There's very little need to change Office versions to 365 unless you are planning on moving the email to M$.
Also, the Print Management app can be run on any Windows system(Start key type Print Management) so any user with print management rights can control the printers, which can be given globally or assigned to individual printers.
Certificates I believe are stored in Keychain. Whitelisting is not a solution. Without proper certificates you have no encryption on HTTPS. You also will not be able to download updates for the MacOS. If you can't fix the stack you will have to reinstall the OS.
And what is listed in add remove programs? You are getting offered updates via Windows Update. Something is triggering that. Did you deliberately install the 32bit version? I’ve not used that version in so long that it might be 2016.