Orchestration: 3 flutes/2 flutes, 1 piccolo 2 oboes 2 clarinets 2 bassoons 4 horns 2 trumpets 3 trombones tuba timpani percussion strings
Premiered on October 28, 1893 in St. Petersburg, Russia, conducted by the composer. Tchaikovsky died 10 days later.
"Pathétique" comes from the Russian "patetichesky" meaning "emotionally charged" or "full of passion" (think pathos, not pathetic.)
Source: http://www.classical-composers.org/cgi-bin/ccd.cgi?comp=tchaikov