“It is mentioned in the first talk that once one reaches sakadagami stage one will not experience
any physical discomfort because of the nature of their subtle bodies in the deva realms.
I am wondering if these entities out of compassion, able to help and guide those in the lower stages to come out of their predicament?”
– Yes. Devas do not feel physical discomforts.
– No. Devas cannot help humans. Only humans (especially those with magga phala) can help other humans by teaching Dhamma. Devas cannot teach Dhamma to humans.
“Can an arhant guide humanity if he/she wishes to do so, or do they cease to exist?”
– An Arahant is not reborn in this world.
– Of course, an Arahant can help others attain Nibbana (by teaching Dhamma) until their death.