You may not lose the link information even after export and import, if you use absolute paths to PDFs. The problem to export to excel is, it can’t export authors and keywords, which contain carriage return, into multiple data cells. Then, this scheme can’t solve the requests, such as, 2 letters from the first author, 2 letters from the second author, if the authors are two…etc etc kind of stuff.
To be able to accomplish such tasks perfectly, all the authors should be registered in individual data cells, with dynamic array size (in the programming world). I have done data export/import between Endnote and the native programming language called Labview, which allows me almost any kind of text tweaking. But, for that, you need Labview or somebody who has it. If you are interested, let me know.