Everything works now, except for saving the files to the current directory....
I don't know the Adobe driver, but the other drivers I know (PDF Creator; PDF XChange) handles nearly everything outside of AutoCAD (e.g. the dialogue). In many cases there is an extra dialogue / ini setting / registry setting which handles this. There are drivers which can be set to the default "use the path of the document" - and have problems if the the software does not pass the path to the driver. For me, I modify the saving-path via registry settings inside my Lisp.
I hope there is a Adobe-specialist who can tell you the way for Adobe, but as said before: I suppose the solution is not in AutoCAD, it is in the driver.