I thought I answered all the questions except what it is made of and the exact concentration/formula, which I won't until the patent comes back favorably, but I told you the density is close to water - extremely close. So close that for rudimentary calculations you can assume water density. Oh, cost and availability I haven't answered either. I don't have an answer to those yet
You can calculate the velocity needed to cut copper with a nanoparticle if you would like. You can easily assume a nanoparticle with a size of 50nm and do it, you can also do it with varying nanoparticle materials since it will be mass dependent. Or, since it was mentioned that the pump head was 10psi you can calculate what size of hole you would need to push your fluid through to obtain that velocity. Then, you can compare it to the hole size in your set-up. Also, knowing the hole size and pump head you can calculate the velocity of the water going thru it to see how close you are to reaching the cutting velocity.