Salaah

Q: When the Imam says Sami Allah Huli man Hamidah, I try to say Rabbana Wa la kalhamd. But before I finish saying it, the imam says Allah Hu Akbar and goes into sajdah before I have finished saying Rabbana Wa la kalhamd. In this case, should I:

1. Stop saying  Rabbana Wa la kal hamd as soon as the Imaam says the takbir and goes into sajdah?
2. Continue to say Rabbana Wa la kalhamd while following the imam into sajdah?
3. Do not say Rabbana Wa la kalhamd at all knowing that I won't finish it in time before the imam goes into sajdah.

Q: If the sun sets while someone is praying Asar, is it complete?

Q: I recite quaran daily in the morning without fail. Also I had started salat but unfortunately I can not perform five time salaat on time because my job is like that. So whatever time of salaat I get, I perform it. Like I came early home so I perform magrib and isha. So my question is that how can I perform Salaah on it's proper time or else I have to perform kaza namaz.

Q: A person doubts whether he is in the 3th or 4th rakaat, and in his mind he has no clue which one it would be. Thus he takes the lesser amount. Should he still sit after the 3rd rakaat and make tashahhud, as there is a possibility that it is the 4th rakaat?

Q: Any wazifa for wealth (rozi)? I do quran tilaawat every day in the morning without fail. But 5 time namaz I am not getting because my job is such that I am not getting time. Whenever I get time, I pray.

Q: I used to pray my daily salah properly on time but as in the future I've lost interest astagfirullah. I really want what I had before with Allah but don't know how to get it. Could you please tell me some ways jazkallah?

Q: I have prayed the Zuhr prayer today. But realised only after Esha prayer that my qiblah direction was incorrect. Do I repeat the salaah?

Q: If someone leaves out a sunnah of the salaah or commits a makrooh action in salaah, will it be necessary for him to repeat the salaah? What if the time for the salaah has already finished? 

Q: What is the shar'ee definition of a sahib-e-tarteeb?

Q: If a person prays a fardh or waajib  prayer sitting down, without a valid excuse, is his prayer considered invalid? I recently heard from a Mufti that the prayer itself would be valid, since he did not miss a fardh element of prayer by sitting down (and not standing). What is the position of the Hanafi madhab in this regard?