Food

For stock, do you mean by 'the rest' that you use the remainder of the bird (carcass) for it, or the rest of the offal? Offal turns stock bitter and murky.

Offal doesn't if its prepd. i always remove the sinew and soak the livers in milk for a day before using them. gizzards and necks just run under water till it runs clear, you want to remove as much of the blood as possible. they add an nice depth

I'd only use them for brown chicken stock. fry them to start the maillard reaction and then add the veg to brown, roast the bones wash then under boiling water and add them, then in with the wine, water and hard herbs, soft herbs at the end when it's off the heat.

Same as fish stock. the heads you can get down She bu market for pence, just pull out the gills and anything red, rinse and put in the pot and you pretty much get a jelly with a lovely flavour, leave the gills in and by christ! it's like eating an ash tray