Short answers, pulled from the story.
The Russian Musical Society launched in 1859 under the joint leadership of Grand Duchess Elena Pavlovna and Anton Rubinstein. The Grand Duchess served as the primary financial backer while her nephew Tsar Alexander II granted Imperial approval.
Music classes offered by the RMS opened their doors to all students inside the Mikhailovsky Palace where the Grand Duchess resided. These sessions took place within the palace before regional branches expanded throughout cities like Moscow.
The St. Petersburg Conservatory opened under Anton Rubinstein in September 1862 as a direct successor to the initial classes. The Moscow Conservatory followed shortly after its founding by Nikolai Rubinstein and Prince Nikolai Petrovitch Troubetzkoy in September 1866.
Following the Russian Revolution of 1917 the RMS disbanded in that same year. An All-Russian Musical Society formed in 1987 intended to carry forward the traditions and cultural legacy of the original group.
Prince Nikolai Petrovitch Troubetzkoy served as chairman for seventeen years while the group eventually relocated to larger quarters. He founded the Moscow branch of the RMS in 1860 when it emerged from within Anton's own house.