I always pre-wash to avoid puckering and dye run in the finished product. The threads and tangling don't bother me. I keep a pair of scissors by my ironing board and just clip them apart.
Ironing secret - take the material out of the dryer while it is still slightly damp. While ironing, it steams itself and comes out completely wrinkle free! Fold loosely and it will stay that way until you are ready to do your project.