Conditions for the validity of Salaah

Q: I want to know that what should be the correct timing to pray ishraq prayer? How much time after fajar aazan can we perform it?

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: If a woman follows one random man in namaz, is the namaz valid (he is not her mahram)? What if there is one imam and one woman behind him and none of them are related, is her namaz valid?

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 made a vow to read two rakaats of salaah everytime I do a certain sin and double the amount of salaah if I do it again. I'm doing this in order to help me completely leave the sin out. I want to know, when I read this salaah, can I make two intentions in one? Example, I read this salaah at tahajjud time so I also make intention for tahajjud.

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: During salaah, I sometimes wear a shirt which has a low collar, so a bit of my upper chest (under the bone below the neck) neck gets visible. Is the salaah valid?

Also, how much portion of the chest should be covered by men during salaah? 

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?