Hello Jørn!
Thanks for the warm welcome! 
The reason why we need the long id is because we are bridging information between PDMLink and another system. Since we have a few PDMLink installations I believe the long id was chosen to distingush between them.
I also believe that the long id is more accoding to the PLMS spec.
Seems that your observations are accurate. I have not done some extensive tests but it seems the long id is always built using the short id followed by the same string no matter what object is retrived in the I*E task so I plan to do as you suggest, make an I*E search for one object and then copy paste it to the bulk data.
Thanks for the tip!
Best regards,
Peter