What are the sons responsibility towards his dead father?

As salam wa laiqum, Dear Brothers and sisters in Islam, My Father passed away on 5th Shawwal, 1442 AH (18th of May 2021). It was a sudden shock for every one of us, he left us without giving us any hint. Being His only son, what will be my duties towards my Marhoom Father? Secondly, I am praying for his Magfirah, but somewhere i feel that i am not doing enough. I want to know how my father is in grave, Is their a way to know that he is all right? Thirdly, My father passed away while i was in USA and by the time i was back in India he was already buried, i Missed his Janaza, For which i will curse my self till my last day. Is their a way to give Kaffara for this Sin? I request you all to please pray for his Magfira... Thanks and Jazakh Allah Khair Ateeq