Before I install the disks for BIAB 2016 in Windows 7, should I uninstall BIAB 2014, or will BIAB 2016 install OK right over it?

If I should uninstall the previous version first, will my musical work be automatically saved, or should I save it to an external drive first?

Note: I am just getting back to BIAB after all-too-long in neglect, which I hope explains the elementary-ness of my questions.