Doubts with regards to one's Hajj being valid

Q: I am an extremely doubtful person. I always have doubts about purification. I always feels I had missed something in wudhu and ghusl. I had performed hajj 3 years ago alhamdulilah. I had performed all thing step by step there was no doubt at that time. After that sometimes a doubt came in my mind whether I had done wudhu and ghusl properly and completely or I had missed something at time of Tawaf-E-Ziyarat. I am also not sure about this. I try to remember but I can't. So should I give dam for this doubt? And my wife would be halaal for me? Please kindly advice me. I am very frustrated with this.

Doubts

Q: If I am doubtful (due to lack of concentration/absent mindedness) as to whether I walked in a carpeted room with napaak slippers and there is no visible sign or smell of napaaki on the carpet, do I regard the carpet as paak to walk on with wet feet and to perform Salaah on, or does it have to be washed? NB: This particular type of doubt has occurred at least twice previously. It is habit to remove the slippers prior to going in to the said room, because I perform Salaah in that room, but as I said due to absent mindedness I could have walked in that room with the slippers, and although there is no visible sign or smell of napaaki, if it was present in the form of a few drops of urine, it would be impossible to tell.

Written divorce

Q: My father signed a written divorce for my second mother. He has given three divorce at one time. It is written like I divorce you, I divorce you, I divorce you. Will it be taken as complete divorce or only one?

Divulging a business secret

Q: I was talking to a friend of mine and I accidently talked about the preparation method of one of my parents businesses which was a chain store for smoothies. If I broke some kind of confidentiality agreement, do I have to ask for forgiveness? The thought crossed my mind but I for some reason kept going with the discussion not knowing if there was one.

Correcting one's intention

Q: I was wondering what would happen if a person for example buys a book with riya, but then makes tawbah and then uses it sincerely for only Allah Ta'ala? What happens in these situations when someone tries to follow Deen but he has corruption in his intention but later fixes it. Will he get reward for it?

Celebrating birthdays

Q: I have a question regarding birthdays. Can we as Muslims celebrate birthdays? I know the answer is no, but a friend of mine told me that if you just cut the cake and only invite one or two friends just to make your child happy, then it's not gunaah and you wont be punished for it. So is this true? Can we celebrate our child's birthday just the way she said?

Losing concentration and composure in Salaah

Q: I have a mental disability where I have psychosis, ocd, and split personality disorder. Sometimes in my Salaah it is not within my control to control the peace of mind and thus my ustaad ruled that for me, being in a state of peace or not does not count for me and my salaah will be fine. My question is, I sometimes do my Salaah when I am at peace but I mistakenly make the mistake of being not calm due to my illness. What should I do in this case with the Salaah that I have ruined in terms of I had already had peace in my mind and intentionally by accident got not peaceful?