Yes, that’s right Channa was an arahant. In the SN 35.87 we can see what the Buddha said about the blameless/blameworthy:
When someone lays down this body and takes up another body, I call them ‘blameworthy’.
So because Channa was not destined to take up another body (be reborn), he was blameless.
That fundamental difference between an arahant and an non-arahant, (i.e. that the arahant has already ended any future rebirths) gives the arahant more options and better judgement when faced with difficult dilemmas in end of life scenarios.
So for a non-arahant to end their own life would perhaps be seen as pointless at best, and even could be counterproductive in terms of developing the the noble eightfold path. That is, they’ll just get reborn again and quite possibly in a realm that is not as conducive to developing the noble eightfold path as the one they just left. This is not to judge the non-arahant, who finds that they can no longer tolerate their own suffering. But essentially they are rolling the dice on what their next rebirth might be—and the odds are not good.
The arahant on the other hand has already secured the ending of saṁsāra, so no more rebirth.
Yes, that’s correct. Any kamma that is performed by an arahant will not bring about a future rebirth. This is because craving has been eliminated for the arahant.
In a AN 3.76 we have a simile:
“So, Ānanda, deeds are the field, consciousness is the seed, and craving is the moisture. The consciousness of sentient beings—shrouded by ignorance and fettered by craving—is established in a lower [any of the] realm[s]. That’s how there is regeneration into a new state of existence in the future.
So for an arahant, no longer “shrouded by ignorance and fettered by craving” there is no rebirth into any realm. There is no moisture (craving) to water the seed (consciousness) that is sown in field (kamma). So no future lives come about.
Yes, sure. They can do what they want, but now they are acting from a position of understanding rather than a position where they are “shrouded by ignorance and fettered by craving” like the rest of us. Their decision making process is consequently so much better.
In SN 36.6 the Buddha explains:
“Mendicants, an unlearned ordinary person feels pleasant, painful, and neutral feelings. A learned noble disciple also feels pleasant, painful, and neutral feelings. What, then, is the difference between a learned noble disciple and an ordinary unlearned person?”
The Buddha describes two types of (painful) feeling: physical and mental.
When the “unlearned ordinary person” experiences painful physical feelings, they also experiences a corresponding painful mental feeling. Whereas the “learned noble disciple” only experiences the painful physical feeling.
So painful physical feelings are experienced by the arahant, but they do not react to physical pain with a craving for the pain to go away and with a craving for sensual indulgence in order to be distracted from the painful condition they find themselves in. This ensures that they make informed decisions when faced with difficult dilemmas in end of life scenarios.