Sajdah and Jalsah

Q: I would like to ask, if I made one sajda only by mistake and forget the second one, is my prayer valid? I heard that the first sajda is fardh only and the other is mustahab.

Q: In jalsa between two sajdah, can we read dua allahummaghfirlee warhamnee in short?

Q: Is there any dua to be read between two sujoods? I have never heard of saying any dua between two sujoods. If someone does not say any dua between two sujoods, does he need to make sajda-e-sahw? I recently heard that one should say " Rabig-Firli" between two sajoods and if someone does not say then he has to make sajda-e-sahw. Is it correct?

Q: I was told that one is allowed to recite any dua in Arabic in the sajda of one's salaah. I understand this does not refer to fard salaah. Is this allowed in the sunnah salaah, e.g. 4 rakaats before zuhr and the salaah after the fard salaah. Please assist.

Q: In salah if I make a pronounciation mistake in sajda or ruku while reciting the tasbeeh first time or second time and if I correct it in the third time, will the salaah be still valid or the moment I make a mistake in sajda or ruku the salah becomes invalid. If the mistake happens in sajda or ruku, if I correct it the total tasbeeh becomes 4 times and in other sajdas it will only be 3 times. Does this difference effect the validity of salah and how to correct myself when I make mistake in sajda.

Q: What I wanted to ask you is that how can one make dua in sujood? Is it allowed for one to make dua in a speaking way in sujood or you just make dua in your heart when in sujood and the second thing is that I want to know how to make dua to Allah Ta'ala and at what time when some one has wronged you, has hurt you etc, what should I pray to just complain about that person to Allah Ta'ala?

Q:

1. Should one's heels be apart or touching whilst in sujood? Is this sunnah? If so which part of the foot should be touching each other as a lot of people are not aware of this?

2. If one recites bismillah in the 3rd or 4th rakaat of a fadh salaah after surah fatiha as though he is going to recite a surah, but then realises and doesn't proceed with the surah, would this require sajda-e-sahw?

Q: Is there any dua that we need to recite between the two sujood of a rakaat in salaah?

Q: During jalsa, would it make my salaah invalid according to the hanafi madhab if I were to recite the dua 'Allahuma aghfirlii wa arhamnee?

Q: Should an imam read the extra duas in jalsa and qaumah when performing salaah in jamaat? Or are these not to be read while performing jamaat?