Not sure about CS5 but why not do a multi select in the place dialog to load your curser and place them that way.
Having the links palete open before you place, it will tell you which pdf is next to be placed
That will be helpful, but in CS3 when I drug an image over my document, the image dropped onto the page. Not so in CS5, which is what I'm looking for.
It should work much the same. Firstly to get it working try a manual place by going File > Place or Ctrl (Cmd) + D. Then tick the "Show Import Options" box, find your file and place it. Try again with the same file and it should drop in using the same settings.
There are a few backwards steps Adobe has made with the recognition of the crop box etc with CS5 compared to CS3 but it shouldn't affect you doing drag and drop. By the way, I use drag and drop all the time and have some very handy scripts that let you drag and drop different pages of the document, LMK if you want them.