Midway through CoT, it occured to me that the people of the Kaensada Hills in Seanchan sound rather like Aiel--feuding clans/tribes, odd customs, considered savage by outsiders. I'm not implying that these two groups are related, but do you think RJ meant them to be similar?

Only in the most general sense.

I haven't read CofT recently, but on a parallel, one of the (many) things I love about this series is RJ's threads of connection between all societies, large and small. For example, in EOTW it talks about how the unmarried women will "dance the Pole" that day, and then in TDR Moiraine and Co. visit a village where all of the newlyweds danced the Pole instead. I don't have books in front of me right now so I don't want to list other examples without checking first, but a sociologist could have a field day writing up all of the connections. It may be just a general description, but who knows? Several times now I've skimmed through something, thinking it really didn't have anything to do with the story, only to find several chapters (or books) later that it's all tied together. This tangent is meant to communicate that I agree with both of you--the Kaensada may only resemble the Aiel in the general sense, but I also think RJ has put an incredible amount of thought into the smallest details, and I also wouldn't be surprised if we were to find out in the next book that there's more to it.