如來(Tathaagata)是佛陀自稱的用語。以下是Ven. Nyanatiloka Thera(三界智長老)的解說:
TATHAAGATA :the "Perfect One", lit. the one who has "thus gone", or "thus come, is an epithet of the Buddha used by him when speaking of himself.
Read the English version of wikipedia buddy, it says very clearly the Tathagata idea has its origin in the ancient canon of Pali suttas. I guess people need to really understand an idea or its origin before ever attempting to discuss it, or else the misunderstanding will result.
The understanding of existence of past lives is something testable and knowable, according to the teachings of the Buddha. You need to develop certain degree of concentration (samadhi) which allows one to investigate the continuous but transient formation of this mind and body in the present, past and even future.