There's nothing wrong with seeking clarification on the mark, and you should if you feel this way. Your university will have some guidelines on marking and classing available somewhere - go and find them, and read the section on dissertations. It'll help explain some of the process, and then you can make sure you understand how the mark should have been arrived at.
I don't think there's anything odd about 17 pages having no marks on - FWIW, I rarely put marks on students' work as I like to keep pages clean for me to re-read, so often, if I'm engrossed in the marking process, I won't put much onto the script. Doesn't mean I wasn't taking notes or assessing what was there. So I'd ignore that.
Is it possible the comment about dates doesn't refer to what you think? For example, might it be that although you included a date, the marker thought it was inaccurate, expected it to be more precise, or expected there to be more dates given for more events? Likewise, is it possible that the note querying who someone is, is an indication that the earlier paragraph wasn't clear enough?
I do think it's really difficult when you have a really different expectation of the final mark than your tutor. Did the tutor definitely know that your marks were mostly in the 2:1 range, and did you ask how this dissertation compared with your record to date?
It sounds very frustrating for you, so please don't think I'm trying to sound negative - just trying to think of the things that might explain what's happened, and the things you might want to ask about, if you have a change to seek feedback.