Short answers, pulled from the story.
Alexander Scriabin was born in Moscow on Christmas Day, 1871, according to the Julian calendar. He came from a Russian noble family; his mother was a concert pianist who had studied under Theodor Leschetizky, and she died of tuberculosis when Scriabin was barely a year old.
Scriabin died on the 14th of April 1915 in his Moscow apartment of sepsis, aged 43. A small pimple on his upper lip, which he had first noticed in 1914 while in London, became infected after his final concert in Petrograd. It progressed to a carbuncle and then a furuncle; his temperature reached 41 degrees Celsius, and blood poisoning set in before surgical incisions could halt it.
Mysterium was Scriabin's projected magnum opus: a seven-day multimedia work combining music, scent, dance, and light, planned for a temple in the foothills of the Himalayas, and intended to transform humanity. Scriabin died leaving only sketches. A preliminary portion, L'acte préalable, was later made performable; Vladimir Ashkenazy conducted a version in Berlin and recorded the arranger Nemtin's two-and-a-half-hour completion with the Deutsches Symphonie-Orchester Berlin for Decca.
Scriabin developed a colour-coded circle of fifths that assigned specific colours to harmonic tones. For his 1910 tone poem Prometheus: The Poem of Fire he composed a part for a clavier à lumières, also called a Luce, a colour organ played like a piano that projected coloured light onto a concert hall screen instead of producing sound. A full realisation using the original colour score and laser technology was given by John Mauceri and the Yale Symphony Orchestra on the 22nd of November 1969.
Scriabin began writing piano music in a late-Romantic idiom close to Chopin. Through a middle period, starting roughly with his Sonata No. 4, Op. 30, his harmonies grew more chromatic and dissonant while still operating within functional tonality. By his final period his last five piano sonatas carried no key signature, tonality was reduced to a distant implication rather than a governing structure, and the music was built largely on acoustic and octatonic scales.
Vladimir Sofronitsky, Vladimir Horowitz, and Sviatoslav Richter performed Scriabin's piano music to particular critical acclaim. Horowitz said that when he played for Scriabin as an eleven-year-old, Scriabin responded enthusiastically and urged him to pursue a full musical and artistic education. Sofronitsky, who never met Scriabin in person, later married Scriabin's daughter Elena.