The cord is approximately 15', but if you use it with a laptop that means you can take it as far as it can connect to your wireless network, so that shouldn't be a problem.
That being said, I wouldn't recommend using ARC, or any room correction software, for such a big area as adjoining rooms. It evaluates an average room curve depending on a Main listening position, and therefore I don't think that it would be of much use for a General listening area. The data collected would be too far apart from one speaker to another, and pretty much irrelevant. I think at that point you could rely on the speaker and amp quality and specs to do the job.
As far as I'm concerned, I've used Audyssey MultEQ XT, XT32, and ARC-1M, and Anthem's is certainly the best room correction software. But, while I think that it has some really interesting results for movies, I've never resolved myself to use any of these for music. Having done extended comparisons with and without RC, I always find the uncorrected sound wider and fuller. That is the conclusion my humble ears and Brodmann areas 41 and 42 bring me to.