If you perform the color calibration, the neutrals are calibrated too. You need to purchase a color calibrator as none of the visual calibrations are any good. There are many types. Typically the Spyders are reasonably priced or look at i1 or colormunki from X-rite and many others. You can also rent these from places like lensrentals.com. One very important thing is that you balance the display brightness with your room ambient lighting. Most of the time too dark prints are caused simply by your display being too bright.
Second problem is that blurb is inconsistent in the appearance of the prints you get back. This is endemic of the places where you can get books printed on digital printers. If you order the same book twice, you'll see that they will appear different depending on which printers they decide to print it with for you and the mood of the operator on that day. Some places will print on photographic printers using light sensitive paper (even on real black and white paper if you want) or using better calibrated printers and bind the product into a book. Those are more consistent but usually more expensive.
Thanks for your suggestion. I'm looking into that now. I read some of the reviews on Amazon & it is beginning to look a little more complicated than I thought. Get back to u soon.