Hi Daniel,
We don't have/use MySQL Workbench, so can't say much about that.
There are various articles with guidance on restoring using different methods, and decrypting encrypted databases in the FAQs:
http://updraftplus.com/support/frequently-asked-questions/
However, in your case, your may be able to deactivate/remove W3 Total Cache by using FTP to delete wp-content/plugins/w3-total-cache.php, and removing its files from wp-content/ (look for files in that directly (not sub-directories) with the words "cache" and "php" in them - I think there'll be one called something like advanced-cache.php and another whose name I forget - remember this is free advice - if you want pro support then there are support packages in http://updraftplus.com/shop/).
David