The main pool at CSR is due to re-open in December. But in January, the pool wouldn't be a factor for me anyhow.
CSR has more ongoing intrusive construction than CBR does. The new check-in area, food court, and restaurant/lounge just opened at CBR this past Monday and its very beautiful. My biggest gripe with CBR was always the 7 bus stops, but its my understanding they now split the bus stops so the buses don't stop at every one of them, which makes the bus ride much easier to deal with. I'm considering a CBR stay my next trip for these reasons.
I am staying at CSR next week, and booked being well aware of the construction. The tower construction as well as the restaurant on the lagoon construction are both in full swing and will still be come January. At CBR, to my knowledge, the only remaining construction are the gondolas and DVC resort, which your room can be away from both.