CH+Police still has zero effect on the Capital, even under Communism - the Capital is ALWAYS 0% corrupt regardless of Govt.
Not in vanilla. (Can't remember about PTW.) Some of the settler factories set up in recent SGOTM games differ markedly between the C3C teams and our team (we played vanilla), simply because in our games we had a corrupted shield in the capital where the C3C teams didn't.
Renata