I use HC110 regularly. I mix dilutions B and H regularly, and occasionally use other dilutions. I know of the syringe method, and I've used it with a variety of developers, but for HC110, I just pour the syrup into a very small graduated cylinder. I have two small volume graduated cylinders, the smallest of which measures from one to forty five milli-liters. This is fine for measuring amounts small enough to fill a small (two 35mm or one 120 roll) tank with dilution H. I pour the syrup into the small grad to measure it, then add water and dump it into a larger beaker to mix my full dilution. I dump water again and again into the small grad and then into the mixing beaker until all the syrup is removed from the small grad, then just fill the mixing beaker to the right level, giving me a properly mixed amount of the dilution I want. I stir with a stem thermometer, to check the temperature and to make sure I don't leave syrup stuck to the bottom of the mixing beaker. This works fine for me, and is more of a pain to write out or read the procedure than to do it. I find this easier than trying to use a syringe on the thick syrup.
As for use, I only use dilution H as a one-shot, but I will re-use dilution B a couple of times within a few hours of mixing if I'm running a significant amount of film. After plenty of testing, my experience is that one half-gallon of dilution B will process a dozen rolls of 120 or 35mm film, or about 45 sheets of 4x5 without exhausting the developer or showing other ill effects on the film. This is generally processing 4 rolls (of either size) at a time, or running 10-11 sheets of 4x5 at a time in a small open tank. I always use a pre-wash to remove the anti-halation dye, which seems to help, and I don't keep it mixed for more than 24 hours. I always keep diluted HC110 away from oxygen- either in full bottles or with floating lids- when not in use, which extends the life of the solution. Frugality is the name of the game here, both for finances and for environmental impact- but I always keep the results on film as the number one priority with how I use the stuff. Keep good notes, and when in doubt, throw it out and mix fresh.
For what it's worth, I like HP5 in HC110 a lot, especially in 120 or 4x5. I get great results with speeds from 200 to 1000, and sometimes higher; it all depends upon the light.