Taubah and Repentance

Q: How can I truly repent from backbiting? I can not find the person I have talked bad about.

Q: What is the ruling on a person who seeks forgiveness from Allah after committing zina publicly? Will their repentance be accepted by Allah, and will they still be subjected to the Shari’ah punishment despite repenting?

Q: Does leaving a bad deed e.g. I was watching insta and it contains music, uncovered girls, etc , become minor or major shirk if left because of someone? Example, my mom came and I did not want her to assume I am watching internet for long or because she had not allowed me to watch and I am hiding.

Q: Muslims who experience conditions like hurricanes, floods, earthquakes, tsunamis then the best thing to do at such times is to sincerely seek the forgiveness of Allah and make sincere Taubah, am I correct?

Q: I repented from a bad Dua is it enough? It wouldn't happen now right? I am really depressed

Q: I have committed a lot of sins to the point where my life is on the line. 

I heard a talk about if someone doesn't have enough good deeds to account for their bad deeds Allah takes it for their state like: making them lonely, taking away their salaah and imaan, etc. I am kinda in that state and I want to repent and make tawbah but I don't know how. 

What dua do I make? Do I pray salaah like normal? Do I read specific durood? Are their specific steps? Do I need to make ghusal? What do I do? 

Please give me a LOT of advice on how to repent and strengthen my imaan (e.g. duas ,extra prayers, etc.)

Q: What will happen if a person commits kufr but later forgets about it? 

Secondly, if you get bad thoughts about Allah Ta'ala and you feel the sensestion of happiness about it but you know thats bad, is this kufr too?

Q: How do I overcome doubts regarding complete forgiveness for all my sins when I sincerely ask Allah for forgiveness for all my sins and how do I build my hope in the mercy of Allah?

Q: If someone has done repeatative sins and he is unable to repent and is feeling Allah's anger on him, what should he do?

Q: Will Allah forgive a murderer or rapist if he repented and the victim also forgave him? Will Shariah still punish him if no one knows about it? Will Allah punish him in the hereafter on the day of Qiyamat because he did not get punishment in this duniya and just repented to Allah, and the victim also forgave him?