Hmm. I suppose that didn't exactly answer the question.
PoodLL saves the files using Moodle's file system API. So they go into the draft files area for the activity in question (NB a "page" has no draft files area when it is being viewed). When the activity is saved, the files are moved into the file area for that activity and submission. It is quite complex and you would need to read up on it all here:
Unfortunately there is no easy to find location on disk.
As for generating a list of students, I can't answer that in a sentence. It is not really clear what you are trying to do. You should look to see if there is a plugin/report that does what you want.