Otherwise idle time can be spent with a rounded pick loosening the strands in the densely packed area toward the portion with gaps between strands. Think of it as part of maintenance.
Constantly loaded and unloaded dyneema-based line is used 24/7 in the fishing industry. It doesn't get retired for years. You can read Samson technical reports on it. I suspect we take loss of color and coating as signs of wear, when it isn't. Stroke the blue stuff and coloring comes off in your hands. Your occasional and short-term loading of <150lb / 70kg is well below a sustained fraction of breaking strength that will fatigue the cord out at 5000+ cycles.
On shorter slings: Yes, you can minimize weight by making them so there's a minimum of length where the cord isn't doubled.
You can make the accessory loops you carry out of 580-650lb Zing-It. If they're used as continuous loops, the load is carried on two legs. With appropriate caveats about the radius of larks head attachments..
There's no reason not to splice any cords you like. Stitching to be sure the sleeve grabs the bury is easy.