Why did the early nationalists persuade Dadabhai Naoroji to preside over the Kolkata Session of the Congress in 1906?

Name the two books that Dadabhai authored explaining the 'Drain of India's wealth' to England.

OR

Who is the author of 'Poverty and Un-British Rule in India'? Mention any one way India's wealth was being taken away to England, as Author of this book pointed.

Name the nationalist leader who edited The Bengalee for several years.

Who came to be known as the Political Guru of Mahatma Gandhi? Give the reason for him being regarded as Gandhi's Guru.