Posts 2,3,4,5 & 7, not unless you are certain it's a young bird, by young I mean 3 yrs or less. Post 6 is the sensible option so as not to be bitterly disappointed ! As 'Kalahari' mentions, cooked slowly (ideally in a slow-cooker) after being cubed is best. I shot two Greylags yesterday morning, both older birds and they are to be cubed, marinated in a 'jalfrezi' for a day then into the slow-cooker with an assortment of seasonal veg on 'high' for 4hrs then 'low' for the remainder.
Incidentally, most wildfowlers I know 'gift' the old geese they shoot....!