Conditions for the validity of Salaah

Q: Will salah be valid if there's najasat less than the hollow of the palm on one's clothing?

Q: I am working on a ship for 6 months at a time. Sometimes we go from America to China and I cannot find the qibla. On sea, our normal application does not work properly so it is difficult to find the qibla. I am performing salaah without knowing qibla direction. Is it permissible?

Q: One day I forgot to offer zuhr salaah and remembered it only 20 min before Asar salaah. I performed the zuhr salaah. Will it be considered as qaza or is it done before Asar time?

Q: I set a musalla (prayer mat) on an impure ground. However the ground had no signs of impurity on it. If my feet get off the musalla (prayer mat) and touch the ground during salaah for just a short period of time, will my prayer be valid? No impurity came on my feet and the ground had no signs of impurity.

Q: Sometimes after getting my haidh, my underwear would become stained with blood and I would perform salaah in this manner. I also cannot recall how many salaah was performed like this. Please advise me what to do.

Q: A person has a urine problem, where if he goes to the toilet, for the next 30-45 minutes he cannot read salaah due to urine drops. If the time of salaah is about to end and the condition persists, does he have to make Wudu and perform salaah, or let the salaah become qadhaa and perform it after the time has expired. (The person is not a ma'zoor as the condition did not last for an entire salaah time)

Q:

1. Is our namaz valid if the Imaam combines two namaazes (zuhr-asr or maghrib-isha) as per Hambali maslak?

2. What is the procedure to be followed by a Hanafi follower if the bus driver does not stop for the maghrib prayer because the Hambali people do combine the namaazes later during isha?

Q: In my college, Maghrib azaan was called four minutes early and I respectfully told the brother to make the adhaan again. He refused but the Jamaat was performed on time though. Will my salaah be valid? Do I have to repeat my salaah and did I do the right thing?

Q: My mom said that we should not pray fajar prayer right after adhaan and we should wait for 15 minutes. Is it true and if it then what's the reason behind this?

Q: “Quarter of the head is approximately the amount of the palm with the fingers.” So to estimate this, do I place my hand vertically on my head or horizontally?

What if some of my hair is showing and some of my awrah from my arm is showing? Do I need to add them up together?