• Yeah, using washers means you can just flip the QR open/shut when checking adjustment rather than taking the wheel in and out of the frame - my note was me thinking aloud that the washers don't need to be exactly the same thickness as the dropouts, as you can adjust the QR's acorn nut so that it takes about the same force to close the lever.

    The tension balance depends on the hub and rim geometry rather than spoke length; if the spokes are too short, the main danger is that they won't engage with the nipple enough. As long as they reach up to the bottom of the nipple slot or just below you should be fine.