Replying to the Azaan and Iqaamah

Q: Please advise regarding the Azaan:

(1) Should Masnoon Dua's be recited during the Azaan? For example, the Masnoon Dua's for entering the Masjid, when boarding a vehicle, when leaving the home and so forth.

(2) If a person is standing during the Azaan, should he remain standing until the Azaan has been completed before he sits down/performs Salaah?

(3) A person enters the Masjid just before the Muazzin is about to commence the Azaan. Is it correct for him to commence Tahiyatul Masjid or Sunnah Salaah at this point i.e. a few seconds before the Azaan? In this manner, almost his entire Salaah will be performed during the Azaan.

(4) It is often observed that those who arrive early to the Masjid (much before the Azaan and within the Salaah time) only perform their Sunnah Salaah after the Azaan has been given. It gives the impression that they were waiting for the Azaan in order to perform their Salaah. Is this correct?

(5) Should one greet a person with Salaam and shake his hands during the Azaan?

(6) Should one respond to the Salaam of a person during the Azaan?

(7) Can one verbally inform others to keep quiet during the Azaan whilst the Azaan is going?

(8) Should one respond to the Azaan heard over a recording or live streaming audio?

(9) Should one avoid 'answering the call of nature' during the Azaan?

Q:

1. Can we answer the Azaan when we are having a bath or in the baitul khala?

2. Is it allowed to enter the baitul khala when the Azaan is on?

Q: Whilst making Du'a, a person hears the Azaan. Should he stop making Du'a and respond to the Azaan instead?

Q: What are the general reprimands and warnings in the Ahaadith against general worldly chat whilst the Adhan is going on?

Q: Should one cease individual recitation of Qur'an and Dhikr whilst Adhan is taking place?

Q: Is it permissible to speak about Deen to a fellow Muslim in the Masjid whilst Adhaan is going on?

Q: If there are multiple azaans being heard at the same time, should one reply only to one or to all that one can hear clearly?

Q: If a person did not repeat the words of the Azaan immediately after the muazzin but only remembered at the end of the azaan at the time when the muazzin reached Hayya Alal Falaah, can he repeat the words from the beginning of the azaan or he should only repeat the words of the muazzin from hayya alal falaah?

Q: When the Azaan is going on, can one continue reading the Quran, is this considered sinful?

Q: I would like to know what is the Sunnah regarding when the Adhan is being performed. At our Ibadaat Khanna a few of our Muslim brothers in Islam, are talking or having a conversation one of them is busy scrolling on his cell phone. This happens on a daily basis and  they are over 45 and 60 years of age.