I would like to make wafer paper like it is used as basis for some Christmas cookies or as used in church (oblates).  This seems to be too basic to be mentioned in usual recipes. Internet search results are so much spammed by recipes using wafer paper that it appears impossible to find clear instructions on how to make the paper itself.  I found only generic instructions like "Use flour and water, maybe sugar salt. Bake."  "Use flour and water" also applies to making pizza or bread and I would prefer to avoid too much experimentation.  How do I choose the ratio between flour and water? What type of flour should I use? How long and at what temperature to bake?  I know this requires experimentation, I am mainly looking for a starting point to reduce the parameters to try. 
Very, very carefully.  Although that's rather tongue in cheek, it's true: slowly and carefully is the key approach. The quicker you try to move, the rougher the shape you produce. You also significantly increase the chance of breakage.  Make an initial rough hole at the center point of your eventual window area, and then cut out to finish the edges. A serrated knife used with a slow, steady sawing motion should work.  Luckily, if you do end up with lopsided, misshapen, or unexpected results, icing and candy decoration can help hide the mistakes :) 