Runggye Adrak had called from a festival stage for Tibetan freedom and the Dalai Lama's return.
Sonam Topgyal's will, discovered by relatives, decries repression and urges Tibetans to unite to solve the region's troubles.
Dolkar Lhamo had asked for the release of her brother's body to his family, and for an explanation of his death in prison.
Tenzin Delek Rinpoche's mouth and nails were black, leading some to fear poisoning, sources say.
The cremation takes place after Chinese authorities refuse to return the body to relatives and supporters for traditional rites.
They detained his parents and five of his siblings when they went to collect his body.
Some want his body returned home for funeral rites, while others want the remains cremated in Chengdu.
Many had traveled in secret from the religious teacher's home county in Sichuan.
Over a thousand had gathered to demand the return of Tenzin Delek Rinpoche's body to his family and hometown.
Tenzin Delek Rinpoche had been recognized by Tibet's spiritual leader the Dalai Lama as a reincarnated lama.
Security forces fill Kyegudo town and cut communications following the sixth Tibetan burning protest this year.
His burning brings to 142 the total number of self-immolations in Tibetan areas of China since 2009.
His group had tried to bring in nets as evidence of poaching after police dismissed their concerns.
He had made offerings to a portrait of the Dalai Lama and commemorated a 2007 US congressional award to the exiled spiritual leader.
Hundreds gather in defiance of Chinese bans to honor the exiled Tibetan spiritual leader.
His arrest comes as authorities clamp down on celebrations in Tibetan-populated regions of China.
The event is observed with fireworks and with prayers in public gatherings and private homes.