Gandhi on Ambedkar and caste

I have been reading Kancha Ilaiah's " Why I am not a Hindu" at the urging of some Dalit friends. Much of it would not pass muster as an academic paper. Perhaps it has to be understood in the same sense as Ambedkar's remarks posted in గాంధీ పై అంబేద్కర్ ఆలోచనలు... . I recall some of Gandhi's responses to the qustions raised which I left in the comments to the above post:
Gandhi’s opinions on several issues seem to have evolved and changed over time. After his often bitter discussions with Ambedkar, Gandhi seems to have finally changed his opinions on caste. Here are a couple of Gandhi quotes taken from “Castes of Mind” by Nicholas Dirks, Priceton Uni. Press , 2001 (page 234).

” When, years later, Gandhi defended himself against attacks by Ambedkar over his views of caste, he wrote that “Caste has nothing to with religion. It is a custom whose origin I do not know and do not need to know for the satisfaction of my spiritual hunger. But I do know that it is harmful both to spiritual and national growth.” At roughly the same time, he stated that “Caste has to go”"

These statements of Gandhi do not seem to be well known. The references that Dirks gave are: Gandhi, Collected works, vol. 63, p.153, vol. 62, p.121

From http://www.bfg-muenchen.de/goralife.htm (Gora's Life:An Outline):
"At Sevagram Gandhi told Arjun, "You should become like Ambedkar. You should work for the removal of untouchability and caste. Untouchability must go at any cost."
Arjun Rao was the groom chosen by Gora for his daughter Manorama (?).

From http://www.ambedkar.org/research/GandhiAmbedkar.htm
"I think, however, that for Ambedkar to stand up to the uncrowned king and anointed Mahatma of the Indian people required extraordinary courage and will-power. Gandhi thought so too. Speaking at a meeting in Oxford in October 1931, Gandhi said he had "the highest regard for Dr. Ambedkar. He has every right to be bitter. That he does not break our heads is an act of self- restraint on his part." Writing to an English friend two years later, he said he found "nothing unnatural" in Ambedkar's hostility to the Congress and its supporters. "He has not only witnessed the inhuman wrongs done to the social pariahs of Hinduism", reflected this Hindu, "but in spite of all his culture, all the honours that he has received, he has, when he is in India, still to suffer many insults to which untouchables are exposed." In June 1936 Gandhi pointed out once again that Dr. Ambedkar "has had to suffer humiliations and insults which should make any one of us bitter and resentful." "Had I been in his place," he remarked, "I would have been as angry."

Gandhi's latter-day admirers might question Ambedkar's patriotism and probity, but the Mahatma had no such suspicions himself. Addressing a bunch of Karachi students in June 1934, he told them that "the magnitude of (Dr. Ambedkar's) sacrifice is great. He is absorbed in his own work. He leads a simple life. He is capable of earning one to two thousand rupees a month. He is also in a position to settle down in Europe if he so desires. But he does not want to stay there. He is only concerned about the welfare of the Harijians."

To Gandhi, Ambedkar's protest held out a lesson to the upper castes. In March 1936 he said that if Ambedkar and his followers were to embrace another religion, "We deserve such treatment and our task (now) is to wake up to the situation and purify ourselves." Not many heeded the warning, for towards the end of his life Gandhi spoke with some bitterness about the indifference to Harijan work among his fellow Hindus: "The tragedy is that those who should have especially devoted themselves to the work of (caste) reform did not put their hearts into it. What wonder that Harijan brethren feel suspicious, and show opposition and bitterness.""