1. In using vmdiskmanger which of the following vmdk should I use? See attached screenshot.
If that was the complete listing of .vmdk files then you'd use the "Virtual Disk.vmdk" file.
2. Is deleting a VM only done by deleting the vmwarevm file in finder or is it more involved?
Have a look at, 
Uninstall a Virtual Machine by Using the Finder or Uninstall a Virtual Machine by Using the Virtual Machine Library.
3. Is is possible to recreate the disk or this is just like creating a new vm?
If you have to actually recreate the virtual hard disk, which means reinstalling the Guest OS (or restoring it from a backup) you can delete the virtual hard disk from the Virtual Machine's Settings (Removable Devices > Hard Disk), add a new one, reinstall the Guest OS and thus keep the other Settings of a given Virtual Machine.
Have a look at, Remove a Hard Disk or Managing Virtual Hard Disks.