Considering Grey Mallard X Blue Fawn Pied Call... what should I expect?

[AvianBrain]

I have a three year old mallard hen that proved multiple times she can sit and brood for a while, multiple times. This was before I purchased my new blue fawn call drake, I was considering letting my hen go broody on live eggs, thus breeding the two. Not completely sure I want to do this yet, but it would be cool to perhaps start founding stock for pet quality Blue Fawn Mallard bantams, as blue fawn is a co dominant gene, it does not require inbreeding or back crossing to calls to secure the trait. My main questions are,
- how many generations of back crossing to mallard bantams would I possibly need to produce some nice blue pet quality mallard bantams?

- the hen I want to use for this first generation is socialy dominant to the drake, as of now, and does not want to breed with the drake, although the new duck's quarrentine just ended last week and are still new to one another, will my hen likely let the drake breed her anytime soon?

- is body shape and bill length in this case actual seperate alleles, or will the offspring pretty much have intermidiate body shape and bill length of the parents?

-does an all drake flock need to be out of sound range of hens for the most part or will just a good seperation space and a non see through barrier good enough?

-how old is too old for many duck hens to safely breed?

And those against any and all crossbreeding, I do understand preserving genetic distinction, but mallard bantams I don't think are in risk of dying out geneticaly.
(Real, Wild-Type Mallards on the other hand are to a degree...)

 

[AvianBrain]

These are the birds I would use.

 

[JacinLarkwell]

@Isaac 0

@Pyxis

 

[Amer]

- how many generations of back crossing to mallard bantams would I possibly need to produce some nice blue pet quality mallard bantams?
If you select the most "mallard" typed birds I suspect it would only take a couple of generations.
- the hen I want to use for this first generation is socialy dominant to the drake, as of now, and does not want to breed with the drake, although the new duck's quarrentine just ended last week and are still new to one another, will my hen likely let the drake breed her anytime soon?
Maybe? I'm not sure if I can answer this question.
- is body shape and bill length in this case actual seperate alleles, or will the offspring pretty much have intermidiate body shape and bill length of the parents?
Body shape and bill length are polygenic (many gene) traits. I suspect many of your birds will be intermediates, but some may be bigger or smaller like their mother and father, though maybe not quite to either extreme.
-does an all drake flock need to be out of sound range of hens for the most part or will just a good seperation space and a non see through barrier good enough?
I'll let someone with more experience than me answer this one.
-how old is too old for many duck hens to safely breed?
I don't think that there is an age where it is too old for ducks. As long as your birds are healthy and sound you should be able to breed them. Their fertility may slack with age, however.