Containers, External Storage and PDFs,

I hope someone can help me and clear things up. I have looked at other posts about this but still feel a bit befuddled. 

We recently converted to Filemaker 12 (we have FMS also). An Overview: We have a field called attachment, in the past the script Inserted a file reference to a PDF file. This database manages Service Tickets. When we email the ticket if there is a PDF in the Attachment field it goes along with it. When the Service Engineers scroll through their tickets they can double click on the Attachment Field and view the PDF if they wish. That being said, the new container options in FM12 seemed appealing. No worry about where the file originated, it would be stored in the external storage in the Filemaker Storage directory and we didn't need to worry about file paths. I changed the attachment field to used the external storage option (Open). Then did the Manage>Containers>Transfer Data.

Problems (or perhaps my confusion)

1. Now when we double click on the Attachment field, it does nothing a PDF doesn't display.Is that because I transferred the data. Previously the script they clicked for inserting the PDf used Insert>File>We store a reference only.  Should I change the script to Insert PDF? Will the data be stored externally. 

2. Also I thought from what I read that when you change a container field to external storage it creates a directory under the FMS>Databases>Container Field Name? I think I might not follow what I read about containers and i have read it multiple times! LOL

3. We also store photos in container fields. I changed them to external Open storage also. is there a way to double  click on an image stored in a container to make it open in a preview mode?

Any help or explanation  would be greatly appreciated! Thank you so much, maybe I can't see the forest for the trees!!!

Caroline