Kodak's instructions assume that you'll make up a stock solution from the concentrate---I forget what the dilution is---and keep that around, diluting it further to make the working solution when you develop. I can't for the life of me work out why they think that; it seems like practically everyone makes the working solution straight from the concentrated syrup.

I'm not sure about the Paterson tank specifically, but 2-roll tanks are usually either 16 oz or 500 ml. You can always measure the capacity by filling it with water and pouring it into your measuring container.

The information at http://www.covingtoninnovations.com/hc110/ is more useful than Kodak's instructions, IMHO.

I've always used a water stop with HC-110 (and everything else) and never had a problem. In theory it might not stop development as fast as an acid stop, but I think for most of us the difference is way down in the noise compared to all sorts of other variables.