Chopping the head is a good diea, as it will bleed out. Blood spoils faster than meat and you want all the blood out that you can.
A dip in steaming water will make the plucking a quick affair. Wear gloves and go at it while the bird is still hot.
8 minutes to prepare a chicken is not crazy if you have the routine down, IMHO. Even at 20 minutes total each, you can get it done in under 4 hours.
Never season to freeze. Also, chickens I'd let sit for a day in the fridge to let it dry up a little. Definitely don't want to age it.
It is not cost effective to raise your own livestock. However, it beats any certified this and that, because you *know* the truth. Fraud in the organic / certified this and that area is just way too tempting! Hunting is a similar activity. Per pound it is expensive, but nothing better than a wild animal IMHO.
George