Firewns questions:
1. For this question and for some of the following questions, we need to remember that PS does not always proceed linearly.
– You are quite right. Upadana involves vaci sankhara and kaya sankhara as well. This is explained in, “Difference Between Tanhā and Upādāna”
2. It is best to think of vinnana as the mindset. With that mindset, one creates energies for future existence (bhava).
– That bhava could be temporary in this life. For example, if one drinks too much, one can make an “animal bhava” and be born in it in this life itself.
– If that person keeps engaging in that activity regularly, that bhava energy (kammic energy) can become strong and could lead to rebirth as an animal.
3. Namarupa are distinct from jati.
– Namarupa arise in the mind. An alcoholic can visualize alcohol bottles, party scenes, getting drunk with friends, etc. All those are namarupa.
– Jati is being born in a certain state, as in #2 above.
4. In the uppati PS, namarupa is the merging of the gandhabba with the zygote to create the “seed” for the new human with a physical body.
– After the baby grows and starts getting attached to “things in this world” the indriya will become ayatana.
– Hadaya vatthu is created at the “bhava paccaya jati” step in the uppati PS.
– Change of indriya to ayatana happens when one gets attached to something. An Arahant has indriya that NEVER become ayatana.
5. In the realm of Brahmas with no consciousness (asanna realm), they have hadaya vatthu, but kammic energy prevents any arammana coming to the mind.
– Without arammana coming in, no citta can arise.
– Kammic energy maintains a fine rupa until the end of that kammic energy. It is as if one is absent from the world during all that time.