Punk, you got a lot of good advice here. I have to say that the Forum was amazing for me back in January, when my neighbor dropped off four chickens at my house in the middle of a snowstorm
You can read all the great advice I got here
(and a lot of the same people who were so generous with their time on my thread have already posted advice for you here).
I've learned so much since the girls first arrived, but I am sad to say the original 4 are now just 2- one was killed by a hawk during a particularly tough patch of winter, and one was hit by a car- I know you asked about letting your new girl out near the road, and I guess I am the unfortunate person who lives in a really rural place yet still lost a chicken to a hit-and-run. It can happen. They don't seem to have much of a self-preservation instinct, unfortunately.
I have a RIR as well, and they are hardy through the winter (I live in New Hampshire). There were originally 2 RIRs, and I did notice a little frostbite before I figured out how to really keep the drafts out of the coop (I never did heat lamps though). I also have a Barred Plymouth Rock, and am getting some Golden Laced Wyandottes and Golden Comet chicks next week- all are supposed to do pretty well in the cold weather, if you're looking for the names of other potential breeds. I am a little nervous about integrating the new little sisters into the remainder of the flock, because the two girls that are left are super bonded since they've spent so much time as a pair at this point. It will be a few weeks before the chicks are big enough for the introduction, but I do plan to try it over night when everyone is roosting, as has been suggested here.
I think Chevaux is the one who said chicken math will get you- she's definitely right about that! I never thought that I'd take to the chickens as I have- in fact, I convinced my poor husband to take a day off from work on Friday so we could have a three day weekend to build a new run for the chickens.
Here are my two girls out on the hunt for juicy after-rain worms: