relic, what do you intend to use the dog for ? as an all rounder i think the bedlington x greyhound first cross is as good as any, bitches and some of the dogs would fall within the size you want.
i freeze it, then just open it up and feed the lot, guts in all, never had a problem with bones, i've also reared litters of whippets on rabbit whole carcesses with no bother .
power hose a few times a week and bleach or jeyes a couple of times per day in one of those one pump action garden stray things, no smell is of great importance when you have neighbours
they sound very handy digger. a lot of dogs give a fleeting mark, maybe only a turn of the head that can go unnoticed or your questioning was that mark ? what i like about the spaniel's marking is that its unmissable.
i would leave lamping til around the year old mark, ferretings a different kettle of fish, personally i would have out with me from 3 months on wards, as Laurie says it clues them in, they learn nothing in the yard.
shells are just made of calcium, not do the dogs a button of harm, i just throw raw eggs into the dog run a few times per week, some eggs the shells , some don't.