#1 - You should be able to use the following Insert Pages settings to do this.
The Insert Pages document will update the quantity to 1 after it inserts pages based on the quantity.
#2 - Use the $FF...$ variable for the quantity in the watermark component to add that information to the PDF. If you want this in a banner page (vs having it in every document) then add a blank page for the banner page, add the quantity (and whatever other content you want to add) and then use pages 2--1 in Insert Pages to duplicate the job.
I have a customer who is asking if it is possible to do two things:
1. Duplicate the PDF file a number of times, where that number is determined by the end-user in the storefront
2. Print a watermark using that same number that the end-user selected.
It is possible that I can make it so that the number sends over a JDF string, but I am not sure what it would need to be in order for a "duplicate" page command to work.