Yes, you should indeed use the 'location' custum field to categorize your contacts. Currently it supports only a single value per contact, contacts that are in multiple locations (in a multivalue field) are not supported yet.
When you choose 'application', it categorizes on the source application where the contact has been stored. When you choose 'location' it will use the 'Location' field in the addressbook.
I have no problemens opening up the PDF from OpenNTF in IE, I'm using Adobe Reader X.
I build this plugin using 8.5.2. I'm not sure it uses specific 8.5.2 java libraries, so it should work fine on 8.5.1.
No thanks Zeff, I have build this application for fun and learning and I'm pleased to know a department is going to try it out!