mistakes

Q: The Khateeb in our district Masjid in the Arabic sermon - khutbah, he reads it as "fakheemil ithm" instead of "ism". A scholar says that this is totally incorrect as Naoozoobillah you are saying that Allah Ta'ala commits great sins. The Khwateeb was asked to correct it, but doesn't do it. He continues to recite in this manner.

1. Is it true that the meaning actually changes and it can lead to kufr?

2. Should the Khateeb be allowed to continue giving the khutbah if he fails to correct this mistake?

Q:

1. How will one correct themsleves if they make the follwoing mistakes in Salaah.

1.1. Doubt which word it is and so reads both e.g. ya'lamoon and ta'lamoon

1.2. Gets stuck and cannot complete the ayaat

1.3. After completing the salaah (nafl or fardh) realise they read an ayah incorrect or missed out a part 

Q: With regards to Taraaweeh:

1. An Aayah was recited correctly. The Imaam thereafter repeated the Aayah and changed it (incorrectly) due to some doubt. Is the initial correct recitation or the second recitation which was incorrect taken into consideration? Does the Aayah have to be repeated?

2. For the purpose of listening to the Luqmah of a Saami', the Imaam remained silent for the duration of 3 Subhaanallaah or more (he did not recite Qiraat for that duration). Should Sajdat-us-Sahw be made?

3. Additionally, if a person because of some disturbance missed an Aayah in Surah Faatihah, or one sentence in his At-Tahiyyat, does he have to make Sajdatut-us-Sahw? To what extent is the Surah Faatihah and At-Tahiyyat Waajib? 

Q: What if a person makes a mistake in the first salam of salah (i.e changes ح to خ) and without correcting it moves to the second salam, is the prayer valid?

Q: If a person refers to a Mufti for a ruling and the Mufti errs in issuing the ruling, what should one do?

Q:

1. If one happens to omits portion of Durood Ibraaheem due to one forgetting it or making a mistake, is the Salaah valid?

2. If one happens to recite Tashahud and one repeats the portion( Ash Hadu...) where the index finger should be raised, perhaps due to getting stuck, should one raised the finger twice?

3. If yes, and it was not raised twice, is the Salaah valid?

4. Whilst in Salaah, during Durood Ibraaheem, one adds the words "Sayyidina" before the words and Names Muhammed (Sallallahu Alaihi Wassallam) and Ibraaheem (Alayhis Salaam), is the Salaah valid?