I bring answer for your 2nd question and the way it is presented is accordingly to a presumption that you are already well informed of the pali terms, so I'll explain them only at further request:
In a conventional body/form, the
citta and the 5
khandhas will remain interdependent until the moment - popularly known as 'death' - when the mundane 5
khandhas and the transcendent
citta go their separate ways. At death,
samatha and
vipassana cease to function (which Arahants rely on to ease the discomfort that is experienced between the
citta and the 5
khandhas), disappearing like all other mundane phenomena. Following that, nothing further can be said.
Continuing to the question of how Compassion could arise, it is already answered above.
My interpretation? They need to take on a form where the 5
khandhas could be present for Compassion to arise. Perhaps that's why Boddhisattvas prefer to stay in samsara to continue their assistance to the worldly beings. When they enter Nirvana, nothing further can be said.
For all those perturbed by this, please do not worry. What's more important is to practise right now and not wait for this human lifetime is extremely precious. And when you are skilled in your practice, you'll see for yourself what all these mean.
