Silkies are prone to B vitamin deficiency, you cam get liquid or gel from the feed store, usually for livestock or you can any brand of tablets from the grocery storeand give her a third every day. Just put it in her beak and she'll swallow it.
Why? If it's a cockerel, just rehome or give away for food. It's that simple.
Size, feathers, wings, spurs, tail, behavior etc are not indications of sex.
90% is pretty good, and it's to be expected for a few mistakes occasionally.
I've never recieved a accidentally male from Mt Healthy.
You're going to want get a permethrine based spray or powder, unfortunately , natural products aren't quite as effective with mites.
I believe the new feed is 18/20% protein? Feather loss can also be a sign of low nutrition diet, cluck and Co is organic but the layer has mediocre nutrition...