Those situations where Talaaq takes place

Issuing one revocable talaaq

Q: One day I had an argument with my wife about something and it got so bad that I got angry and used the word divorce. However, after some time, the anger subsided that same day and we both made peace. Is our marriage valid? If yes, what is the atonement for it? And if not, what is the solution?

Issuing a talaaq while being forced

Q: My elder brother, recently and was forced to get divorced from his in laws. He was under so much pressure from them, and he was alone at his rented house, and they all forced him to say yes for the divorce. 

But now he is saying that he has not said from his true heart to his wife that I need the divorce from her. So please advise if the divorce is done on his wife or not, because my brother is saying that he has not given her divorce by his heart, but was under pressure from his in laws.

Issuing three talaaqs in the absence of one's wife

Q: I constantly have waswasa regarding different things, such as fears of losing important things and intrusive thoughts about divorce. 

Recently, while driving alone, I had thoughts of talaq, and I became worried about accidentally uttering the word and losing my wife. To counter these thoughts, I ended up saying the statement three times "main tumhy talaq deta hon" with my wife's name, thinking it would stop my mind from repeating it in front of her. 

However, I later read that divorce in isolation might still be valid. I also consulted an Imam at the Masjid, who assured me that the talaq is not valid. I would appreciate your opinion on this matter.

Divorcing one wife by saying her name but the another wife's name came to mind

Q: If a person has 2 wives and he, intending to divorce one says her name then explicit words of divorce like "Maryam I....(explicit words)" but at the time of sayings the words he has his other wife who he didn't want to divorce come to his mind.

Does it mean he accidentally gave divorce to the other wife (named Zainab) which he didn't intend to?