Thank you everyone for getting back to me which this great advice! Based on your feedback, I have decided to totally scratch my initial idea and revamp my approach to starting chickens. Rather than going the transportable coop/run kit approach, I have decided to get a much larger permanent coop within a MUCH larger permanent run. I honestly believe you all kept me from making a very big mistake resulting in some very unhappy birds. This online community is so fantastic!
I'd really like to try and find a coop I can purchase, rather than building my own (a serious lack of skills and proper equipment needed on my end). I am now considering purchasing this model of coop instead...
http://snaplockchickencoops.com/standard-coop.html
and completely enclosing 1/2 of the space under our 2nd story porch as their run. The space under our porch is tall enough to stand under without having to bend over (so I'd say about 7 feet tall), and would provide 12x7 feet of floor space for them to move about in. The coop would be inside of the run, elevated on a stilt frame so the chickens could walk under it. With this new approach, I have a new set of questions:
1) Is a run of this size adequate for 3 Australorps?
2) Does anyone have experience with this sort of coop? My biggest concern is whether or not this style provides enough insulation and ventilation for 3 Australorps to keep warm in our extremely cold Minnesota winters (without the use of any heat lamps or mats).
3) How about the size of this coop? It need to be large enough for 3 Australorps, but cozy enough to 3 Australorps to stay warm in during the winter, right?
4) Is having chickens under our porch a terrible idea? It is a large and airy space, and I would fill the run with sand, but will smell be a big problem?
5) Lastly, during the winter, should I keep their heated waterer and feeder inside the coop, or outside of it? (I'm concerned about coop size if the answer is inside).
Again, thank you all for being such an amazing resource! I want to make sure I don't move ahead with anything on impulse.