1. I just updated mine to the new version. Don't worry. Just install the new version directly over the previous one, and DO select YES to the option of "save the previous installation". It will take a backup on its own.
2. Yes sure, you can install both versions on your pc, just rename the installation folder name to something else, eg Spooky2-215 or Spooky2-305, you can manually move saved presets or BFB after.
3. It's always a good idea to back up your stuff to other media than the hard drive that is holding the C:\Spooky2 folder. If your hard drive goes bad, and you only have the Spooky2 backup from the installer, well, that backup is trashed too if your entire hard drive is trashed.
To back up the entire Spooky2 install, just copy the C:\Spooky2 folder to your USB thumb drive or SD card.
If you just want to backup the minimum to get all your personal data only, see this post: https://www.facebook.com/groups/spooky2/permalink/1550696278425603/
For more details, please check the link: