Kufr

Wife denying the husband the right to take another wife

Q: If wife and husband have argue about marrying more than 1 wife, and the husband says are you going to deny that it is aloud to have more than 1 wife, and the wife says "yes, I deny that", does the wife fall in kufr by denying this? Also is the marriage contract between the husband and wife annulled? Who's responsibility is it to get the marriage contract renewed?

Taking an Oath for acts of kufr

Q: A person who promised or said or took a qasam etc. to commit an act of kufr or commit an act of kufr at the time of death or join shaytaan or follow him or become brothers with him or accept his offers or accept it at the time of death or die as a non-muslim or commit a sin etc. Does it suffice to seek Allah's forgivness alone?

Is it kufr to say that a certain medicine cures

Q: Is it kufr to say that this medicine cures like acne as example. Like is it kufr to put your trust in that medicine? Before I read a fatwa of someone asking that question but they said its not, I don't really remember. But now I am hearing that Allah cures him not the medicine, so I am confused. So whenever I say this medicine has a cure for this, I think is the cure from Allah or Allah put the cure in the medicine. But I know if Allah wills he wouldn't let him be cured by that medicine. Did I commit kufr?

Utterances of kufr

Q: If a muslim attributes to himself an other religion by saying, for example, "I am a Jews" or "I am a Christian" or "the christian are better than muslim in aqida". Does such a person become a kafir even if he uttered the statement jokingly and even if he did not know that it is kufr to say such a thing?

Cursing Allah Ta'ala (Naudhubillah)

Q: I should not be saying this but it is bothering me. When something bad happens to me I lose my temper and say very very bad things about Allah Ta'ala like he is not merciful, he is cruel, and I also curse Allah (Naudhubillah). Do I become a Kafir on saying this? Are all my good deeds wasted by saying this? If I don't become a kafir, can I repent for these sayings?