C++ was my first "real" language (after BASIC and assembly, as a teenager) but I haven't touched it since about 1996. I used to love C++, but don't miss the manual memory management, linker issues, 2-stage compilation/linking, data types being different sizes on different architectures, etc.. Java has proven to be a worthy replacement for the level of stuff I work on (business/app-level logic).
Maybe instead of making any large decisions about direction / technologies up front, it might be good to play around with some of the old CSV files and maybe write a little demo app and show people what can be done, etc.. There wouldn't be any risk involved in that, as no one would be going "live" on the CDC site. Unless the CSV files contain top secret info or something... That said, I'd have more time in the fall/winter to play with it - don't want to spend many hours when it's nice outside.