I'm sorry no Silkie breeders have responded to your questions. I have had a few Silkies, and have seen mixes, and I can only relate what I've observed. I also have foot feathered Marans and crested Cream Legbars that I've observed in my own mixes.
My experiences....
Silkies (according to my understanding) that are pure white are likely recessive white...so 50/50 chance of chick being white if bred over a blackish bird...BUT you are putting that over an EE white....which might be recessive or dominant depending on the history. So let's assume both are recessive, it takes 2 genes for recessive, and breeding those 2 would give 2 genes (1 from each parent) so white chicks. If the EE is dominant white...white on all chicks again. It would take a few breedings over a black bird (as dominant black is primarily targeting black) to figure out if you've got dominant or recessive.
My experience with foot feather...passes most of the time, ditto with crests, for the first generation. It begins to drop out by generation 2 and beyond. Though I've noticed 1st generation is not as cleanly foot feathered...meaning some are rather sparse.
The Silkie feathering seems to fall away pretty fast...most Silkie mixes I've seen are normal feathered. A quick "AI search" (understanding that's limited reliability) does indicate it is a recessive trait. So with my personal experience and what AI is telling me, I suspect your chicks first generation will have normal feathering. You'd have to line breed back to the Silkie parent to get a 50/50 forward.
My experience has been the same with the melanine. It seems to pass pretty quickly too as most Silkie mix chicks I see have red combs. You'd have to line breed back to the Silkie to fix that trait. Apparently the fibromelanosis (which is dominant) also needs an inhibitor to be expressed, which I suspect is recessive?
Hopefully an experienced Silkie breeder will step in and give some advice.
Good luck with your mixes.
LofMc