Good questions. Here is more relevant information.
1. The appearance of a Buddha is a natural process and no one has control over it. The present maha kappa just happens to have five Buddhas. Normally many maha kappas go by without a single Buddha.
Several suttas state how rare it is for a Buddha to be born, and for a human to be able to comprehend Dhamma. A good example is AN 5.143, a decent translation at: “At Sārandada“.
It describes five rare occurrences:
– The appearance of a fully awakened Buddha.
– A person who explains the teaching and training proclaimed by a Buddha.
– A person who understands the teaching and training proclaimed by a Buddha.
– A person who practices in line with the teaching.
– A person who is grateful to those who help him/her.
2. Vedic brahmins were indeed “good recordkeepers”. They were really good at memorizing bits and pieces of Buddha Kassapa’s teachings and passing them down through generations.
– This is why there are so many “overlaps” with vedic teachings. However, they did not use Pali words in many cases and adopted Sanskrit names: karma for kamma, nirvana for Nibbana, atma for atta, etc.
3. It is rare for any living being to “transfer” from one cakkavāla to another.
– But those with well-established miccha ditthi could be born in other cakkavāla.
– Even when Bahamas and Devas from closeby cakkavāla come to listen to desanas here (especially those by a Buddha), they go back to their own cakkavāla.
The new series of posts on “Origin of Life” will get into some of these details. I have transferred other relevant posts to that subsection so that most of the relevant information will be there.