On top of what foneil said, it's not ideal to try to recover applications from Time Machine that required an installer (like Microsoft Office, Adobe Creative Cloud, and also ESET Cyber Security) because they normally have more files set up and configured outside of the Applications folder. Using their installers would be the best method.
With the Facebook message, it is a genuine message and they do have a help article on it. Because it is detected by what's happening on your account, I would suggest taking the time going through your messages you've been sending, your Activity Log (you can access it from your Profile) and also going through settings (click on the arrow on the top right, then click Settings) to check for any applications you have that you really don't need and to secure your account.
Thank you very much for the help, it really was helpful, I did not know that about TM files.
My FB account is, I believe, safe, i change my passwords often and use zero applications. Are you suggesting that it really is a genuine message meaning I do have malware? I checked their help section and, as far as I comprehend it, they think I may have malware because of the content I post - which is surprising to me since most of my posts are articles and news. Hence, I think it is just algorithm that evaluates this (e.g. the websites, links, etc.)
Thank you in advance
smiles