I use the Durst U70 enlarger regularly and love it. I have the original user manual filed away and would be willing to scan it for someone if they still need it.
To answer your questions, McNigel, you can use it for 35mm. The 105mm will work, you just can't make very big prints. For larger prints, I use a 50mm lens. You need a recessed lens board for that lens. It's a bit awkward to use since the lens is tucked inside the "tube", but it works. With the 50mm lens, it's all manual focus though.