so that's about 0.000762 c not really fast enough for interstellar travel. It would take about 4, 462 years to reach the closest star, and at that speed, relativistic time dilation would be negligible.
It would however, be fast enough so that any sizable piece of space junk, say a gram's worth or so, should pretty well vaporize any material plating on the ship.
this is incorrect. Magnets have no effect on weight or mass, or any other property of the ship.
Stopping where? There's nothing between us and the nearest star, and it will take over 4000 years to get there. That's a long time between fill ups.