ok im gonna answer guestion 2 first.
-the material is like a thick paper with a plasticy feeling finish on the colored side, almost like photo paper,  its the paint smaple cards you can find in hardware stores
to answer question 1, glue. first all the pieces are cut out of the paint samples, than glued to a piece of paper to create the design, then i cut out the design, which now has a paper backing to make it stronger and glue it to another sheet of paper.
3. yea id be really stoked to have these made into shirts, is there a website i can use? any help on this would be awesome