Let's think that the tech allows for some gravity manipulation, as is evidenced by the ship layouts. They're designed like ships at sea, so there must be artificial gravity in the ships otherwise they'd be built like the ships in "The Expanse" ie: vertical with decks at 90 degrees to the thrust making artificial gravity by engine acceleration.
Sorry, but No. Word from Above (Sir DB himself, I believe) is that the ED universe has no artificial gravity. It's why space stations and the habitat ring on Imperial capital ships rotate. As for internal design, the ships are designed with a clear up-and-down because they need to be designed to function in a gravitational field; "down" must be in the direction of the landing gear. Aligning "down" witht he main engine thrust vector would not make sense, as the main engines do not provide thrust for most of the time a ship is in space; the FSD distorts space, rather than accelerates the ship, so the ship is in zero-G the whole time it is in Supercruise.
This is why bullets and lasers have damage falloff at range (as if through an atmosphere), ships have maximum speeds (as if flying through air), and materials/cargo cans stop in space instead of flying away at whatever velocity they initially had.
You forgot one scenario: exploded spaceship debris, which eventually stops expanding, stops rotating and comes to a full stop. But they can't have placed inertial dampeners and little powerpacks scattered throughout the ship's hull, so that every major piece of debris of an exploded ship has its own self-powered intertial dampener. That'd be just silly.
The "Ships have maximum speeds" is easy to solve: the retro-thrusters automatically fire if you exceed the "maximum speed" your ship's navigation computer is programmed with. Which does of course simply move the question, to "Why do all the ship manufacturers program in such a ridiculously low flight speed?". Since the inability to infinitely accelerate away from danger is the cause of millions of ships exploding every month, I can only assume it's a conspiracy of the ship-builders.
The same simple explanation cannot, of course, apply to your other examples. Lasers are prone to the inverse-square law so damage fall-off is to be expected, but kinetic weaponry damage fall-off is, of course, ridiculous. My head-canon is that it doesn't happen. Same goes for cargo and debris magically coming to a halt, in defiance of Sir Isaac Newton. If I think I observe such phenomena actually happening, my observations must be faulty.
If one must assume that the observed phenomena are real, then another explanation must be made. The aether is both an unsatisfactory answer (if the aether exists, how come the planets don't slow down and plummet into their stars?) and prone to copyright abuse (the spaceships in
Star Wars canon are steered by an "aetherial rudder"). I would postulate a more reasonable alternative:
Invisible space ghosts.
They fly around and grab hold of stuff to stop it from moving.
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