On our tarps that we use for shelters have paracords on all of the grommets that stay attached even during storage. Usually about two to three arm spans.

50 feet is pretty managable. I was taught to never cut a rope unless you absolutely needed to. This is especially true for temporary setups like a clothes line. Our troop had some metal buckets with various lengths of rope with whipped ends. If you got off your butt and dug through the can you could probably find the length you needed. The rule was if you cut a rope you had to whip the two ends that you cut.

For long lengths of cord, I coil most of it neatly then wrap a bird's nest/daisy chan around the coil to keep it neat. For shorter lengths you can wrap it like a hayanawa.