@firewns: Welcome to the discussion forum!
#1. There are two ways to attain Nibbana (which means stopping the rebirth process):
- In both, one MUST realize the unfruitfulness and danger (because of the unavoidable future suffering in the lower realms) in staying in the rebirth process.
- For that, one needs to understand the real nature of this world of 31 realms. That real nature is expressed in Tilakkhana (anicca, dukkha, anatta).
#2. Now, if one figures out the true nature by oneself, then one is a Samma Sambuddha, like Buddha Gotama or Buddha Kassapa before him.
-It is much easier to LEARN the true nature of this world FROM such a Buddha or a true disciple of a Buddha. These are Arahants.
– Of course, a Buddha or an Arahant attain the same Nibbana.
#3. Attaining the Buddhahood is not an easy process; see, “Paramita and Niyata Vivarana – Myths or Realities?”
– Since a Sotapanna has learned (and comprehended) Tilakkhana to some extent FROM either a Buddha or a true disciple (Ariya) of a Buddha, he/she would NOT become a Buddha.
– This is why a Bodhisattva will never become a Sotapanna even if he learns Dhamma from a Buddha. One who is making paramita to become a Buddha will not able to learn (and comprehend) Tilakkhana from anyone else.
– Furthermore, an Arahant has already stopped the rebirth process, and is also called a Buddha sometimes (Buddha means “bhava” + “uddha“, or someone who has stopped future bhava, and thus future rebirths). But an Arahant is not a Samma Sambuddha; that title is reserved for one who attains Nibbana via his own efforts, like Buddha Gotama.
#4. Your other question has been discussed here:
“What happens to an arahant after death”
P.S. I just added another comment to that topic.