Q:Are Theravada and Mahayana mutually exclusive?
Buddhists believe in the unity of all human beings. Hence, it should be their moral obligation to treat Theravada and Mahayana as traditions not mutually exclusive or incompatible versions of Buddhism. Instead, their aim should be to identify aspects shared by these two traditions as complementary and allied schools in order to unify diverse and divergent Buddhist philosophical views.
The major point of differences between Theravada and Mahayana is the ideal of the Arahant, the enlightenment of the disciple esteemed in Theravada and the ideal of Buddhahood attainable by all, emphasized in Mahayana. Despite the two different ultimate goals of enlightenment, the adherents of Buddhism can meet and work together bearing in mind the spirit of the fraternity, kinship, harmony and solidarity of world Buddhism.

Q: Are there other versions of story of Siddhartha
No we think there is only one version for Siddhartha story

Q: Harvey defines ethics and morality as "other-regarding".(p 2) What about actions towards self, such as suicide or self abuse? Does harmful action directed at self also considered an apunna action? suicide is not an acceptable response to suffering in general. Certainly self-harm is unhelpful and a cause of future suffering, and suicide does generally involve self-harm. in theKandaraka Sutta.[40] the Buddha says, ‘one who seeks delight in suffering ... is not freed from suffering. One who does not