To re-state and clarify what others have said, when upgrading your 2006 to the current version...
1. Yes, the male voice will be lost.
2. Nothing will change with the clock. From 2006-2008, the navigation display turned off when it timed out if you didn't press the "okay" button after starting the truck. From 2009-2014, the display shows the clock screen instead. Updating the navi software does not add this functionality to the 2006-2008.
3. You'll need the "second" disc, but it will be included automatically if needed based on the year and model of vehicle you select when you place the order through the website or over the phone. There is no charge for the second disc when required.
4. In the past, the update has been offered with free shipping and/or a discounted price at random times. I don't recall any promotions since they started a multi-year discount plan a year or two ago.
5. Since 2006, there have been updates to the maps and points of interest (which are 1-2 years old the moment the newest version is released). Arrows showing direction of one-way streets were added. No other significant functionality has been added. It will look and operate the same as your original version.