Can I use this with a netti pot or other sinus was system?

Yes..., I use about 2 capfuls in the normal neti pot saline solution and it does wonders. Undiluted is too strong for me.

Can I premix a week's worth of this? I would like to make a big batch, then portion out through the week.

SJ, I'm not sure what you mean by making a big batch? What I do each morning is fill my nasal rinse bottle (way better than a Nettie pot) to the line, microwave it 35 seconds, add one packet of the nasal rinse solution (I don't make my own) and then top it off with the Alkolol. I'be learned that the Alkolol at room temp cools it down a bit hence I microwaved at 35 seconds earlier. I've learned not to top off too full or when I put the top on it overflows and is wasteful. I find the Alkolol very soothing to a very dry and irritated nasal and sinus cavity lining in the winter. Alkolol was recommended to me by my ear, nose, and throat specialist. I love it! I don't think it would be good to mix up in advance and use later. I think it would water down the mentholated value of the Alkolol. Also,you don't want to allow bacteria to grow so using it immediately after mixing is best. You can buy pre-mixed packets anywhere so it's easier. I get mine at Target. I also rinse my bottle and cover every time and dry it upside down on a cloth to prevent bacteria growth. Hope that covered your question.

how do i disinfect the blue tube?

Probably the most convenient way, is with Hydrogen Peroxide. Personally, I use Chlorine Dioxide drops to sterilize just about everything of this sort (netti pots, mouth guards, fruits and veggies, etc. (except for metal items). LTS, be very careful what you clean with, particularly since it can end up in your body. Plasticizers (released from microwaving it) or alcohol (often preservatives), plasticizers (leached from the bottle), could find themselves in the body.

Does this product have an expiration date?

Yes, it does, it is on the label of all bottles, but it is also embossed on the flap of the boxes for the kit version. Hard to read, but it month and year are there too. The three boxes I bought from Amazon last year, in November 2016, show an expiration date of June 2019.