Times of Salaah

Q: In Ssaudi the Adhaan is given at the very moment the salah time enters. In India, except for maghrib, there is a delay in the Adhaan being given for all the other 4 salah. The delay varies from places. Suppose Bangalore Asr time sets in at 4.04 pm but Adhaan is called at 4.30 and jamaat starts at 4.45 pm.

My question is, should the sunnah be offered after Adhaan or can one offer the sunnah once the time of the salah enters even before the Adhaan is called out?

Q: I leave work before maghrib and on my way home maghrib prayer time enters. I cannot offer maghrib when the time enters and only offer maghrib prayers just before Esha prayer. Is it allowed to offer maghrib prayer before Esha if you dont offer it on time?

Q: I would like to know if I read Fajr Salaah and after I finished, I saw the time was 5:39. Few seconds later, when I checked the time again It was 5:40 and sunrise is at 5:40. Should I repeat the salaah or is it okay and within the time?

Q: I reside in an area and noticed that both mussallees and trustees of the local masjid are unmindful of zawaal, this is mainly on a Juma as we come early for jumah.

I find that people are performing nafl salaah during this time including the trustees and Ulema. The other masjids that I attend during this time either put on a light or a sign that say zawal.

I would like to know the following:

Firstly when is zawaal and how long does it last for? Example the times I see on the calendar for today as well as salaah times from crescent mobile says zawal 11:59am.

Does this mean zawal sets in at this time or ends at this time?

During this time of zawal what should be done and what should not be done?

Should I bring this to the attention of the trustees and will I be accountable For this if I don't?

This has been going on for the past 3 years or so. I dont want people to be offended and neither do I want to commit any wrong actions, thus when attending this masjid I look at zawal time on my phone and as a precaution I commence my nafl salaah 10 mins after the stipulated zawal time.

Q: If a person delays the esha salaah and only performs it after midnight, will the salaah be valid?

Q: If I started my zohr namaaz at 4:00pm due to being sick, and asr namaaz came in at 4:03 whilst I was reading my salah, do I have to repeat the zohr namaaz?

Q: A Salaah Time Table has one time named as 'Sehri' and another time named as 'Fajr.' Of these two, when does the time for Esha Salaah end?

Q: If I wake up 15 minutes before fajr, can I pray tahajud or not? 

Q: In our country, fajar prayer starts at 3.50am and magrib starts 6.50pm. What is the correct time to perform tahajjud prayer?

Q: Can one read his maghrib and esha salaah in the time of maghrib before boarding the aeroplane considering that it is quite difficult for one to read his esha salaah on the aeroplane especially when there is no salaah facility on the plane?