You can do a backup if you follow these 2 threads:

Using FAR+SEFP with a DB2012 DB2020 phone (Guide) - Top Sony Forums

and

***CUSTOMIZATION and BACKUP OF YOUR PHONE***INSTALLING ICONS WITHOUT FAR/XS++*** - Top Sony Forums.

In respect to the firmware files, you can try googling or you have the site's downloads area but, you have to meet some requirements.