Welcome! I moved from Dallas 14 years ago, it took me about a year to adjust to the colder average temp but nothing like the coldest days you get there. This is a dry climate so the cold is not that biting wet cold you get down south. There is rarely ever ice, just snow and since we have the most sunny days it is melted and off the road, usually by the peak of the morning commute. When it snows it does not get dirty, and it glitters in the light. During the hottest days of summer the nights are cool and comfortable. I love it here and I will never move back.
The things to worry about for you would be the altitude change and the dry climate. Drink lots of water, find a good lotion, and take it slow(you will get winded very easily). The biggest change for the chickens is the altitude change, I would look in to it to be safe. The heater also would be a good idea.
If you move around the Highlands Ranch area and have questions PM me, or have questions in general.
....On another note, I finally get time to spend with my girls and I am sick. Maybe I will be strong enough to spend some time with them Sunday.