I have two of them, and they are really the best you can get for 35mm (in my humble opinion)
To my knowledge they use two different types of lamps, both with a GZ 6.35 socket.
One holder is for Philips 6604 and the other holder takes Philips 13139 or Osram 64615 lamps.
The autofocus works with the 40/2.8 and not with any other lens (you can still focus manually).
The 40/2.8 is excellent so don't bother to change.