I would like to submit a provisional patent via EFS to the USPTO. There is an option to submit as a registered eFiler. What reason would I want to perform the submission as a registered eFiler? If I submit the PPA unregistered, can I register later and have the PPA attached to the registration as if I had submitted as registered?
Yes, you can attach it latter as long as you know the application number and filing date. If you lost that information you might have some hoops to go through to show that it was you that filed.