If BLST fuel is defined, does this change ZFWCG/TOCG (maybe because pumps start to shift fuel around)? If so, where do I get the new values needed from?

The ballast fuel is described very well in a post that you might be able to find here dated about a month after initial release.Ballast is not normally required except when the aircraft is lightly loaded but full of fuel. Under these conditions, the ballast will be retained and not pumped around during the flight. It is not available for the engines except with manual intervention.