Insulation has no bearing whatsoever on how easy the coop is to clean. The insulation will have to be covered by plywood or something like that to keep the chickens from pecking at it ANYWAY... in fact if you do NOT insulate, and have open exposed-stud walls, that is a bit *harder* to clean just b/c of the irregularities caused by the studs sticking out every X inches.
While you could certainly keep well-chosen breeds alive and even healthy without insulation, I honestly do not see the point in letting a coop be colder than can reasonably be avoided and in your climate I would think that insulating would certainly be worthwhile if you were willing to do it. (Unless you are planning a fresh-air type open-front-even-in-the-winter coop, in which insulation is utterly pointless... but I doubt you are).
The main thing I'd say is to give your chickens plenty of room by building BIG. Not just so they have indoor space to while away long boring cooold winter weather, but mainly because it is extremely difficult to balance air quality, nondraftiness, and temperature in a teeny tiny coop such as one *could* potentially build for just 2-4 chickens.
If you can possibly manage to build a walk-in size coop, at least 4x8, you would not regret it, and bigger would be better. See my 'cold coop' and ventilation pages (links in .sig below) regarding designing with cold winters in mind. Put the ventilation that you will be using during wintertime on the usually-downwind end, high on the wall, and with the roost as far as possible away from that end (especially important the smaller the coop is)
Picking cold-hardy breeds (esp. those with pea/cushion/etc type combs as opposed to large single combs) makes life a lot easier too.
Good luck, have fun,
Pat
