1) The document is a letter from Rabi to his friend Sohel explaining that Rabi's father recently passed away from lung cancer caused by years of heavy smoking.
2) Rabi's father ignored warnings from Rabi and his mother about the health risks of smoking and the dangers of nicotine in tobacco.
3) Rabi explains that his father's death has been a great shock and they are worried about how their family of seven will survive financially now that Rabi's father was their only earner.