Filament silk questions

I ordered a small sampling of silks from Hedgehog Handworks (very nice folks with a great selection of metal threads and the full Au Ver a Soi line).  Playing around with the Soie de Paris, I am now in love with filament silk.  What was I thinking with stupid old spun silk?  Really?  I might as well have been using cotton. Oh, that's right, I can get it easily without all this on-line color card nonsense!

Anyway, for those of you have have greater filament silk wisdom than I (not hard I freely confess), I have questions!  First of all, I am looking for something suitable for doing the pattern daring on the Mary of Hungary smock.  I think silk would work best, and there really is no point in using silk unless I use filament, but it's also a smock and white and will thus need to be washed.  Let's face it, sauce will end up on the front of it at some point.  What is going to happen to the filament when I wash it?  Will it be a tragic loss?  Or will it be ok?  I'm ok with handwashing, just not so much drycleaning.

Second, has anyone used the kanagawa embroidery silks?  These are Japanese silks, and come on 20m cards, which is more length than you get with the Soie de Paris (5m spools), I'm just not sure if it's plied the same way, or how it compares.  I would assume it a good quality thread since that's what they use for the amazing silk embroidery they do in Japan, which is more complex than the opus anglicanum I want to do.

And lastly, when doing medieval style silk shading, how many shades of silk do you really need?  The technical references I have assume you have an insane palette of threads I am guessing would not be available to the medieval embroiderer, and most of the extant pieces I've been able to find decent pictures of don't seen that detailed or sophisticated in the shading but it's hard to tell when looking at pictures on computer screens.