Generally, you do not need to request a copy of the PHYSICAL file. Further, such a request requires that someone in the visa office pull your file and make a copy of it, which means you lose your place in the queue - people usually report longer processing times when requesting a file copy. Thus, unless you have a strong reason to get a copy of your file, all you normally want are the computer notes (FOSS/CAIPS/GCMS) because these tell you status information.
I have done both. The electronic notes generally come about 30 days after the request (and are usually 25-30 days old). The one time I requested a physical copy of my application I was not concerned about processing time, because it was for a rejected application. It took around 3 months to receive the material. It was interesting, as it showed where the officer had made notes. But the most interesting information was still in the computer notes. While refused, because it is subject to litigation they continue to add notes to the computer record, and one of the notes was some interesting communications between their legal counsel and CIC. I'd have expected the information to be redacted, as it is privileged communications, it was not.
At any rate, just ask for the computer notes - and normally they will just e-mail them to you.
