Da'wah to non-Muslims

Q: I don't know everything about Islam but it is my duty to forward the little knowledge about Islam that I have. So I want to ask how to give dawah to a non Muslim. Should we start with inviting them to Islam or start a conversation and invite them later on?

Family problems

Q: My question is about my father. He is totally on a wrong path. I mean few years back he was a very nice man. He had a fear of Allah and Masha Allah he saw the prophet (Sallallahu Alayhi Wasallam) two times in his dream (ziyarat). He always used to pray juma prayer, and tazbihaat, and Quran. But now since the last two years he doesn't even go for Eid prayer. All the time he is busy in watching television and his language has become extremely abusive. No roza, no namaaz, nothing. He knows everything but does not want to do anything. Now when my mom or me are praying in front of him, he doesn't even decrease the volume of the TV. He is totally lost and he doesn't love my mother at all. Please tell me some dua by which he can become a namazi and a loving and caring husband. Actually he had an affair with one of my aunts. A very close relative of mine, my Mumani that is my mothers real brothers wife and my mom came to know about the affair after 14 years. Then when she came to know about the affair, my father apologised to my mom and broke whatever relation he had with that woman. But now he has left that, but when he is at home he doesn't care about anyone. It looks as if he is always in tension. Lost in his own world watchng TV with very high volume, or using a laptop for long hours. He doesn't talk much to his children or wife. My parents are married for 30 years. Please give some solutions. Me and mother are extremely worried about him.

Dua of Ka'b Ahbaar

Q: There was one sahabi who was a jew before, most probably Abdullah ibn Salaam or Kaab Ahbar (ra), who said if I did not read this particular dua, the jews would turn me into a donkey. Which dua is it?

Insect killers

Q: Is it permissible to use an electric/electronic device to kill off insects such as cockroaches, ants etc. Presumably such devices have a heating element under a plate and insects are literally roasted to death or simply electrocuted.