You're going to get all kinds of solutions to your questions about prewashing fabrics, but here's what I do. I prewash everything to avoid shrinking and running when I make traditional quilts and so I can be sure the fusible will adhere when I make art quilts.
I wash using the gentle cycle, with hot wash, warm rinse and no detergents. When I take the fabrics out of the washer to go into the dryer, I cut all the loose threads. It's the dryer that ties everything up in knots, not the washer. After 20 minutes in the dryer, with no dryer sheets, there are a few more threads that need trimming, but none of the fabrics are tangled up so they are all ready to be folded and put away. I don't iron them until I'm ready to use them. I lose way more fabric in squaring up for the first cut than I do in unraveled edges from prewashing. This system works really well for me.