BSOD On this computer but did not receive response on Acer post

As you say, you don't know what is on the system. Another reason for cleaning everything up, it is very possible that the previous owner has installed software to track what you're doing to steal at the right moment. This is a dirty example that actually happens often in regards to credit card fraud or exploiting the system to install ransomware.

It is strongly recommended to backup all personal files you don't want to loose, then wipe every drive (or replace) and clean install Windows.
What many do when they get a used machine, wipe the drive and install Windows all over again, for above reason.

It all looks clean, but no opinion about all the tracking cookies (no idea if they're malicious or not), but you will want to remove Office and download a fresh installer if you're not planning on starting fresh and want to use Office.

No worries, the most important thing is that you backup important files to an external hard drive. In case of software customization check their support for how to back up the customization and how to restore it.

For backing things up, I recommend to triple check everything. I've recently clean installed my system, but today I figured out I lost a few important files because I didn't check everything properly. (I do create system backups weekly, but those files were a few days old)