You don't NEED to insulate, but at the same time, if you do it correctly it will be useful and you won't regret it. (By correctly, I mean using proper material, either rigid foamboard or batts are fine, and with TIGHT carpentry so mice are not so apt to take up residence in there). It can make your life and your chickens' lives rather easier in a cold winter.
Electric heat is unlikely to be necessary for well-chosen breeds in Mass. but it can't hurt to have it available just in case. Also remember there are lots of other things you can do to moderate coop temperature that do NOT involve electrical heating - see link in my .sig below for ideas.
A heated waterer, or heated waterer base, is not essential but is awfully nice to have if your coop temps spend a lot of time below freezing. It saves you quite a lot of toting fresh water out there multiple times a day
No, vegetable oil will NOT keep your water from freezing, nor will any other additive
Thus, it is POSSIBLE to run a coop in a cold-winter area without electricity, but it is a pain in the patootie and better avoided if possible.
BTW do not neglect to ensure sufficient wintertime-friendly ventilation in your coop -- yes, you do need to have vents open even in the winter, and generally more vent area than most people expect, because chickens put out vast amounts of humidity and humidity is a BIG cause of frostbite at really-pretty-mild temperatures.
Good luck, have fun,
Pat