. If I perform the virustotal scan on a file, will it's website always indicate this fact?

In my experience, VirusTotal scan keeps track of the file hashes. For every upload it does a lookup to check if a file has already been scanned before. I checked their policies, but couldn't find how exactly hashing and lookups work and if there is any ageing process.

Submissions to virus total are not normally automated for general software and developers aren't obliged to submit their built executables to VirusTotal. One can argue, it's not the responsibility of developers to notify the AV vendors about a new version of their software. If you ever submitted your own software there, the process can be upsetting, especially when several AVs misclassify your own software as malware and their page to submit a false positive report does not actually work or no one cares on their end to fix a false positive. Another example, not all files in the WindowsSystem32 are scanned, I've just submitted an executable from the Windows folder and it hasn't been scanned before. I've also submitted a dll that was scanned a year ago. It just means no human or application has uploaded that particular file before, and that's ok.