So, I know that the Navis Primer is the rulebook about Navigators, but is there any Navigator fiction out there that I could read for inspiration? If I wanted to read about Inquisitors, there's the Eisenhorn and Ravenor trilogies- Is there something similar for Navigators?

There's a Navigator that features rather predominantly in the second Enforcer novel.

Citadel Journal 18 does have some old background on Navigator families. Alot of it has already been repeated by FFG, but it's still worth a read.