Nice to see you again. Good to see you're having so much fun at GEH!
re: "So how important is the nozzle size and the pressure?, or is rate of addition the more important factor??"
It's hard to imagine all the alchemy and uber engineering that was engaged in to make Polaroid products, but this film, http://thelightfarm.com/cgi-bin/showvideo.py, starting at 7:56 minutes gives an idea of how important extreme precision was to Kodak, not all that long ago. (Spoiler alert: NOT )