I'm also very interested in making some vacuum fixures soon so I'll be watching your progress keenly. I have not done any real investigation yet but I guess the thinner the ID of the tube the better because I don't think high flow volume is required and keep tube lengths to a minimum. I mean long thick tubes will need a bigger vacuum tank to handle the initial suction. Not sure but I don't think all types of quick connect couplers that are designed for pressure will seal properly when used for vacuum so maybe just confirm that with the vendor.
I'm curious when you say "compressor", do you mean vacuum pump or will you be using a compressor with one of those compressed air vacuum generators or is there another way?