I've done a whole hog before, about 106 lbs as I got it from the butcher.

If you get it from the butcher, it will have the skin on.

If you get the hog yourself (i.e. feral hog), you'll have to dunk it in 140 degree water for a couple of minutes and then brush the hair off; this is called scalding. This is a pretty major operation if you're not prepared for it.

For preparing a hog for whole roasting, Google search on "Pork Slaughtering, Cutting, Preserving and Cooking on the Farm". This is a USDA booklet with a lot of good information. It will go into details on how to scald a whole hog.

For roasting pigs, do a Google search on "Preparation of whole roasting pigs" by the Virginia Cooperative Extension, dated 2000; it might provide some useful hints and tips.

Good luck.