Qa’dah and Salaam

Forgetting to sit for the last qa'dah

Q: A person was performing a four rakaat fardh salaah. After performing the fourth rakaat, he did not sit for the qa'dah but forgetfully stood up for the fifth rakaat. He then made ruku and sajdah in the fifth rakaat, sat for tashahhud and made salaam.

What is the status of his salaah? Is his fardh salaah valid or does he have to repeat his salaah?

Method of making salaam in salaah

Q: What is the correct way of tasleem in namaz. What I know is, at the end of salah, should I start saying salam (assalamu alaikum wa rahmatullah) when my head is towards the qibla and continue saying salam while I turn my head towards the right and complete saying salam after I complete turning my head. This completes the first salam. Should I turn my head towards the qibla then I should start saying salam when my head is towards the qibla and continue saying salam while I turn my head towards the left and completes saying salam after I complete turning my head. This completes the second salam.

I have observed the following three cases in case of three imams who are leading prayers. Could you please clarify if the salah is valid in these cases.

1. At the end of salah,the imam turns his head towards the right and after completely turning he says salam. Then he turns his head to the left after completely turning he says second salam. Is salah valid in this case? Why I am asking this question is , I have read somewhere (I guess it is from a shia person) that if you turn your head during salah your salah will become invalid. In this case the imam first turned his head to the right, by the time he starts saying the salam his salah has already become invalid.

2. The imam completes the first salam properly as per my understanding. But he starts saying the second salam when his head is turned towards the right and continue saying the salam while he turns his head towards the left and completes saying the salam after he completes turning his head towards the left. Is salah valid in this case?

3. At the end of salah, the imam completes saying salam when his head is towards the qibla then he turns his head towards the right. Then he turns his head towards the qibla and completes saying salam when his head is towards the qibla then he turns his head towards the left. Is salah valid in this case?