Does this mean that everything she deleted can be retrieved from the server?
The server is in the hands of the Obama government...so no... not ever... maybe in 20 years... don't hold your breath.
Some may be retrievable with good forensics. Some may be retrievable with extremely good forensics. Some may have been overwritten too many times to retrieve. But one of the things about Windows is that it writes things to the disk when swapping, so very interesting things may be stored in unexpected places on the disk
Not if the person wiping the server had any knowledge of forensics. Heck, I would have deleted all of the e-mails, done a DOD wipe on the drives, then had the drives physically shredded and put brand-new drives into the server.
Of course, even if that happened, that raises other problems. First is the obstruction of justice charges resulting from the deletion of the e-mails and wiping the server. Then from a reading of the statutes that have been referenced, even having deleted the e-mails won't help, because they have the printed copies that already proves that the classified information was on the server. Just having that information on an insecure server in her possession, even if it was as a result of gross negligence, is still a felony.