Its not necessary to use Yupo as a tissue support, you can use almost anything that will hold up in the warm water developing bath. I got my yupo from a print trade paper supply firm, it should not be expensive to buy 100 very large sheets and it should be available nearly everywhere. Photopaper can be used and so can wall paper.

I have looked in to making half tone seperations, since I do not have photoshop, it can be done with the seperate+ plug in for Gimp and the newsprint action. I have decided that with modern profiling software there is probably very little advantage in doing it that way. Of course, I could be very wrong.

The iso Lab specifications for CMYK printing on a coated white substrate are easily googled. By printing a test chart with reasonably linear negatives, to the iso spec for CMYK, the process can be profiled in the same way as an inkjet printer is profiled. Also it is possible to use soft proofing to see what your colours will be like. I am shure it is possible to do theese things with half tone seperations too, but I am not shure if there is any advantage.