Whatever the method of space bending used by the warp drive, it allows for two ships to chase each other within visual range. And lest it be suggested that optical distortions are at play there (either in-universe, or just for the sake of dramatic license), we also have situations where two ships at warp come close to touching each other (the two NX ships in ENT mating) or the opposite (the Prometheus splitting up).
Warp bubbles thus seem to be extremely compact things, actually. Moreover, with a bit of effort, you can hide them inside a cloaking field... Them being an environmental hazard looks extremely unlikely, then. (Hey, even space within the fields themselves only degrades after centuries of exceptionally intense traffic!)
To quote Douglas Adams, "Space is big. You just won't believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space."
I've always thought that chasing down a ship to attack them while at warp is a bit silly in most cases. You have to warp space in front of you quite some distance so I don't see how you would have visual on another ship until you were able to merge your warp bubbles at exactly the same speed. You can't be in the same bubble with one ship going faster than the other - the ship in front would just be able to cruise along in the other warp bubble and save it's energy? If you are in separate warp bubbles at different speeds the odds of you synchronising your warp bubbles seem pretty slim when you consider that a slight differential would lead to the other ship overshooting by light years but its plausible that Federation ships tracking other Federation ships should be able to do this since they use the same tech and have coded transponders. Since they would have to be in separate warp bubbles the Enterprise might have been better off dropping out of warp for an instant, let the Vengeance fly by and plot a different course. Not so easy to pull off when being pursued by a Federation ship since they will find it easy to track you with your transponder I guess.
Still it should be harder to follow non Federation ships than they make it out to be in episodes since you have to travel slower than the ship in front to detect the trail and they are bit vague on what happens to a trail when you warp space to follow it - I would have thought the original trail would get over-written. I wish I understood sensor ranges better. Range of plot, I know...