First, the idea that the "streaks" are actually particles hitting the warp field is a fairly widely accepted explanation for this phenomena. Given that Starfleet ships are limited to a few thousand times the speed of light, it is not possible that these things are stars going past.

The fact that Trek ships navigational shields are invulnerable to lasers is stated in "Conundrum". The technobabble used to explain this was actually created by using the 'Technobabble generator' in "The Nitpickers Guide for Next Generation Trekkers, Volume II", written by Phil Farrand. The babble generator allows you to make up cool-sounding technospeak from sets of words using random numbers - it's rather tounge in cheek, and great fun. I have no idea if the phrase 'trans-static flux effect' makes sense to anybody, but it certainly doesn't mean anything to me!