XnView Software

My pictures (about 140'000) are stored on a NAS so that i can work with them on several Macs.
- Where should i install the program? On each Mac or on the NAS (in the Folder of the Pictures)?
- If i copy the Folder with all pictures to a security-disk: Does the catalogue still work?
Thank you for ...

Thank you Franky

If i add new categories to an existing category they are listed in order they were created. Can i change the order manually?
Mit freundlichen Grüßen
rumo