1. You don't need to use special detergent at any time. If it gets clothes clean, it'll get your quilts clean.
2. I highly recommend soaking each color separately in a sink of warm water to check for bleeders. Those
can get washed in a lingerie bag on gentle, with 2 Color Catchers per load. If you don't use a lingerie bag,
those small pieces could end up lost in the rim or lip of the washer.
3. Precuts will usually ravel in the wash. That's my biggest pet peeve. (I once got a batch of scraps that smelled smoky and so I washed them in a lingerie bag. What a mess to try to iron. Almost wasn't worth the hassle.) I wouldn't wash precuts that don't bleed in the sink.
4. You could try soaking each precut in a bowl with warm water and vinegar. Vinegar stops bleeding, usually.
Bottom line, precuts can save a lot of time and pain for your arthritic hands, but they are prone to shrinking and raveling, so you'd be least bothered by NOT washing any that don't bleed.