To do the job with 4D v17 R6 could be a little bit more complicated.
We did some changes for the final Catalina after R6 was frozen for last testing.
If this is your first try to do notarization (your question 3 gives that impression), I suggest to try it first with 4D v18 Beta, even you don’t want to use v18 today for deployment. Only as a learning tool, as it reduces the effort for the first step (prepare the package for the 4D parts, while you still need to handle your own parts, like your own plugins, you need to make sure your own pictures or other files are “good”, etc).
So, do start with v18, follow the steps described here:
If you don’t want to use v18, read at least the parts for “CHECKING THE NOTARIZATION STATUS” and “STAPLING THE TICKET TO YOUR APPLICATION”