If I click “Select All” and then “auto-update” will paperpile perform the auto-update function on every single item in my library?
Select All will select all the papers in the current view. This is the large number at the top of the right-hand column. Directly under the number you can also see how many are selected. You can use that to verify before running an auto-update.
In general, we do not recommend running an auto-update on all the papers in your library at once - it may take a long time and some of the services we check may temporarily block your IP.