I think you're referring to the Four Noble Truths:
the eightfold path is the path that Buddha taught.
Nobody taught the Buddha. He came to his own conclusions.
Buddha taught the path leading to the end of suffering.
the buddha taught it for his next 45 years.
Yes it is writings of the Buddha. The Buddha created it.
Nobles women taught their children mannors and culture.
Buddha taught everybody how to practice
The three religious belief systems are buddhism, confucianism, and neo-confucianism. They are taught by Buddha and Confucius.
Buddhism began about 2500 years ago. Buddha means Enlightened One. The name was given to a prince named Siddhartha Gautama. Buddha taught for 45 years the Three Universal Truths, Four Noble Truths, and The Eightfold Path.
I'm not sure what you mean by 'save', but buddha taught Buddhism to many people and how to meditate, become enlightened etc.
Buddha taught the Eightfold Path so that people could stop being reincarnated into more suffering.
No one. They were not educated. Only the nobles.