Why don't you just edit the menu item to launch the PDF file directly if that's what you want it to do?
I not sure why you want to use the Output Window so much, either. Just output the Find Results to a file collection and then use Print Folder from there. The Output Window is a leftover from Opus 6 and pretty much obsolete these days; I expect it will be removed entirely in Opus 10 and nothing forces you to use it in Opus 9.
As a reminder, Ask one question per thread. This thread was a mess from the first post. 