[Grey's not as space racist as Cain, because the Imperium of Man is absolutely the unchallenged champion there, but after that little three-decade genocide attempt by the Covenant, she's not keen on aliens. It does help somewhat that Brainy is basically a human palette swap (not to mention fellow prisoner), and Grey manages a polite face, though her good cheer comes across with somewhat sharper edges than it had when she was talking to Cain.]

Slipspace is only space in the mathematical definition, to be precise. It's an 11-dimensional continuum without spatial dimensionality in the same sense as the three in Euclidean spacetime.

Navigation's only possible by computer. A smart AI's preferable, but dumb AIs are capable of it. They end up with more temporal drift, though.