this is how I understood it worked. You can't apply what you know about physics to those ships becasue they don't operate in this time and space. the ship never moves faster than about .90 light and that would be really going fast. The ship creats a "warp field" around it that allows it to drop into another layer to time/space. In this new place time is no longer a constant and distance is not the same. For example moving a foot in trans space would be like moving a million miles in our space and time. as far as maneuvering they also use gravity type drive produced by the warp engines. this is why they don't do flying against the rear bulkhead and get smashed during acceleration and when that approch suns as such, gravitational pull has little effect. this same force is used to slow, speed up, and maneuver the ship. this is also way the primary hull doesn't just break off the secondary hull having that large mass attached by that single member, little or no real forces are acting on it. the ship creates it's own gravity fields which allows it to attract and repel from plantary bodies and such. the ship is desinged around trans warp dyanamics and with out all of it's support fields in place it can be easily damaged. Why does it move like it does? becasue like a modern aircraft it's completely computer controlled. All the crew does is tell it where they want to go and the computer factors in about a million things that are happening around it in the unverse and then maneuvers the ship in a safe efficent manner. They do use the impulse engines for powered foward motion but this is assited by the gravity (warp engins) helping it to steer, pull and stop the ship with undue stress on the ship.
If you notice when there shield and structural integrity fields fail those torpedos ripe through it like a paper mache but when active have little effect. the whole ship exist in several magentic bubbles that hold it together, maneuver it, protect it and allow it to slip into another place and time for shot periods to travel over great distances without having to go that fast in out reality.