If its below freezing do you need to keep your kill on ice? Or can you wait & quarter him out in the morning?

clean him, skin him, hang him and spread him and if its much below freezing your liable to be quartering him with a saw the next morning.
I have kept meat hanging for days in the winter, just wrap it up in the daytime and keep it in the shade.

the fridge at the grocery is about 40 and meat keeps for a week before they grind it into hamburger

I'd at least gut it and wash it out pretty quick after killing it. Then, if it's freezing I think I'd be okay with hanging it out in the cold overnight.

If you get the guts out it will stay alot longer, all the really bad toxins in an animal are in the stomach, and intestinal track and you need to get them out as soon as possible.

get guts out and skin when body is still warm and house off to get as much blood as possible then cover with plastic to prevent meat from drying, should be fine,

Keep in mind meat can not be frozen, defrosted and frozen again without cooking,

Lower than 40 (about 34 is ideal) degrees is safe to leave hanging for several days...dry aged meat is hung uncovered for much longer. So you've got nothing to worry about as long as it's very clean after gutting.

pig meat does not need to be aged

I've heard this before but don't understand the reason why.
Seems like it would be OK to me if you defrost in a fridge. If you defrost on a counter top I can see issues.

Please explain.
Thanks,
Shay

There's nothing harmful as far as health concerns if you do this, as long as you are thawing properly in a cold environment. What is effected is the quality of the meat. Unless you are using an ultra-fast blast freezer for freezing, large ice crystals form in the meat when freezing. (The slower the freezing process, the larger the crystals.) These ice crystals actually act as little knives that cut holes in your meat. When you thaw the meat, this means a greater loss of moisture. That's why you always have puddles of watery blood when you thaw meat. If you refreeze it again, you are repeating this process and leading to more moisture loss and texture degradation. What you end up with is a dry-ish piece of meat with a bit of an odd texture. If you end up braising or stewing the meat, this is less noticeable...but in most cooking applications, the meat will not respond well.