I can see some answers here but they don't go into details at all. Essentially, I have one piece of code that needs to access the drive with few uploads and downloads. In this case, what are the charges for using it? I can see quotas for a million queries but does that include upload/download? b) Is there a way to do it without publishing? The testing one only allows 100 users but I was wondering if the same piece of code calling it repeatedly would only count as 1 user while granting all the functionality.
When you create a project on Google Developer Console it is technically in the testing phase.
This can be seen on the OAuth2 consent screen in dev console
While your app is in testing you can have 100 unique users test it. The email addresses of these testers is added on the same screen.
So when a user runs your app and authorizes your application to access their data they are a user.
It doesn't matter how much that user does it's still a single user.
Google Drive API is a request based quota. Each request you make costs one point against your quota. If you have a quota of 50 then you can make 50 requests it doesn't matter if they are uploads or gets or lists. It's a request.
However if you do a file.list and it returns additional pages of data each request to get the other pages will cost you the single point.
If it's the same person that logged into the same Google account, then it's one user.