I need to lengthin a drain pipe for a sink in the wall. I need to add about 8 inches horizontally and then have it come out of the wall to the sink. After cutting the pipe and adding the longer section, do I just smear the glue inside the fitting and on the pipe and stick them together? Is it just one type of glue or do I add some epoxy and another type of glue? What I am getting at is what is the glue that is used to glue the black plastic drain pipes? How much do you use? What is the best tool for cutting the black drain pipe? A sawsall???