Hit is not a do-or-die issue as a tank. It helps with threat, if you don't need help with threat then don't bother.
Also, DW DK's get 3% hit from talents. So you need 5% from gear to cap your specials (including next-attack abilities i.e. Rune Strike).
If you're not having threat issues, then get rid of some of the hybrid threat gems for stam. Also, what food buff do you use? If you're eating Fish instead of Expertise food, well there's an opportunity to trade something weak (AP) for something stronger (Exp, or if you get rid of some purple gems for blues, Stam). Also, +10 stats is a weak gem for a tank, replace it with +30 stam. In fact, I'd ditch almost all the hybrid gems for stam and see how your threat fares - you will probably surprise yourself.
As far as spec and glyphs go, my DK is fail and so I have no real authority to answer those questions.