Obeying Allah Ta'ala before one's parents

Q: My sister was given 3 talaqs and after her iddat she made nikaah with her ex and are living together as a family. My mum and some family members accept them and mum does not talk to us or want us. She is staying with sister whose ex husband sat for itikaaf so mum goes to them whenever they need her. We cannot visit or call our mum. She has a lot of anger for us but she is happy with other family members who go against shariah. Please advise us on this.

Fasts missed during one's teens

Q: I am 25 years old. I missed out fasts during my teen years and I am unsure of how many fasts I've missed. Probably around 30-40. I do however want to give kaffarah for those fasts. Should I re-estimate how many fasts I have missed and pay a kaffarah for each fast, or should I pay one kaffarah for all the missed fasts? Also, how much should one pay for a fast? Or how many people should I feed to suffice for one fast? Jazakallah in advance.

Dawat and tabligh

Q: I have a question about importance of dawat and tabligh. I want to know if tabligh is fard or wajib or anything else? Tell me anything about dawah in Islam in Shariah. I want to ask that if I don't do dawah do I go to paradise or am I a real muslim that Allah accepts?

Ahaadith relating to Dajjal

Q: I just want to know about Dajjal. Some people narrate hadeeths about him being a son of Adam and will be born to a couple who would be barren for 30 years while others narrate a story about him being chained on an island. What should we be believing? What's correct and what's not? Please do enlighten me.