Short answers, pulled from the story.
Ivan Pavlov was awarded the Nobel Prize in Physiology or Medicine in 1904 for his work on the physiology of digestion. The prize citation stated it was given in recognition of his work through which knowledge on vital aspects of the subject had been transformed and enlarged.
Classical conditioning is a form of learning in which a neutral stimulus comes to produce a response after being repeatedly paired with a stimulus that naturally triggers that response. Pavlov discovered it almost by accident while studying digestion, when he noticed his dogs salivated at the sight of the technician who fed them, before any food appeared. He and his assistant Ivan Tolochinov developed the concept jointly in 1901.
Ivan Pavlov was born on the 26th of September 1849 in Ryazan, in the Russian Empire, the eldest of ten children. His father was a village Russian Orthodox priest, and Pavlov initially attended a church school and theological seminary before abandoning a religious career to pursue science.
The question is genuinely disputed. Pavlov's writings record a wide variety of stimuli including electric shocks, whistles, metronomes, tuning forks, and visual stimuli. In 1994, A. Charles Catania cast doubt on whether a bell was ever used, though Roger K. Thomas of the University of Georgia later identified three references suggesting Pavlov did use one.
Pavlov accepted Soviet funding and honours but openly expressed contempt for Communist policies. In 1923 he stated he would not sacrifice even the hind leg of a frog to the Soviet social experiment. He wrote to Stalin in 1927 protesting the treatment of Russian intellectuals, and after the murder of Sergei Kirov in 1934 he sent letters to Vyacheslav Molotov criticizing the mass persecutions that followed.
Ivan Pavlov died on the 27th of February 1936 of double pneumonia at the age of 86. He was buried in the Literatorskie mostki section of Volkovo Cemetery in St. Petersburg, and his study and laboratory were preserved as a museum in his honour.