First off, yes a lip added in front will keep stuff from spilling out.
And secondly, insulation is definitely a personal choice... I live in chicagoland, and we get very cold winters here, but I do not insulate. I have an uncle living in this city with chickens as well, who also, does not insulate. Chickens do well in cold, especially if you have more than 1 or 2, because they will keep each other warm. Cold air is not a problem as long as it is not drafty and moist. If you have the extra time and money to insulate, and it will make you feel better about having them in the cold, then go for it. But I don't think that it's necessary
And secondly, insulation is definitely a personal choice... I live in chicagoland, and we get very cold winters here, but I do not insulate. I have an uncle living in this city with chickens as well, who also, does not insulate. Chickens do well in cold, especially if you have more than 1 or 2, because they will keep each other warm. Cold air is not a problem as long as it is not drafty and moist. If you have the extra time and money to insulate, and it will make you feel better about having them in the cold, then go for it. But I don't think that it's necessary
