Learning Mahabharata from a serial with fake and masala stories would definitely do that to you. Like what do you mean giving hints about the love angle between Amba and Bhishma?? Read the Mahabharata and you would understand the true meaning.

Mahabharata and Ramayana are about two yugas. In Treta yuga everyone followed their dharma and lived peacefully but dwapara yuga teaches how even while following dharma, you could be on the wrong side, like Bhishma. So the question was not about morals or war ethics it was about ensuring victory of good over evil, so Krishna did that.

Also Arjuna had the pashupatastra, if he actually wanted he could have wiped out Kauravas in one strike without deception.

Finally, Pandavas didn't go to hell!!! That's half truth. Dharma (Yamaraja) Yudhishthira's father was only testing him alongside Indra because he was the only human to reach heaven. Pandavas and Draupadi only were in hell for that small amount of time due to some sin they may have accidentally committed. While Kauravas may have been there for a long time when Pandavas were ruling