Some answers to your questions:
1. Preinstalled software
Although I don't recommend this, and I would go to uninstall everything (unless you know what each one it is and you use it), yes, you can restore the pre--installed software from AdwCleaner's Quarantine. Here it is a link about it (which I never used): https://support.malwarebytes.com/hc...dwCleaner-delete-or-restore-quarantined-items
Please, if you want to restore these programs, do not do that now. Wait for the cleaning procedure to complete first.
2. Microsoft Office
As I already explained, the Enterprise edition is for big companies and not for individuals. You had a pirated license for Office (as well as for other programs) and this is one of the reasons you got infected. If you want to have Microsoft Office (Home or Pro), you have to buy it from Microsoft's page. Have in mind that some sellers sell this kind of licenses to ordinary users. They claim that they sell in a low price, but this type of licenses may cause issues at a later stage. If you don't buy from Microsoft directly, make sure that the license you are getting is Retail.
In case you just want an Office Suite, no matter it is Microsoft's, you can try some free alternatives:
Home | LibreOffice - Free Office Suite - Based on OpenOffice - Compatible with Microsoft
www.freeoffice.com - Download
Apache OpenOffice - Official Site - The Free and Open Productivity Suite
WPS Office - Free Office Download for PC & Mobile, Alternative to MS Office
I tried the first two above, and I like them very much. You can open Microsoft Office documents with them and Microsoft Office can open files created with them.
It's your decision. However, do not install anything yet.
3. Encrypted files
I asked you and I think you didn't reply about this. Are your documents encrypted? If yes, the usual reply is that they can't be decrypted now. But we will do some search about this, at the end of the procedure.
4. Corrupted files
We are going to check this after I review your fresh logs in a while.