Гулаг (gulag) is the acronym for "Гла́вное управле́ние исправи́тельно-трудовы́х лагере́й" which translates to "Head management office of correctional work camps". And if you're going to go for all incarcerated, the number is actually somewhere in the 2.1mil range in the US, because hey, jails are a thing.
Sorry that you're wrong on all three points.