Qadha

Offering Qadha prayer does not omit the sin of deliberately ignoring to perform the prayer on its time. That sin needs real repentance and sincerely seeking forgiveness.

Wassalam.

If you deliberately broke any the fast of any day of the month of Ramadan, you need to pay Kaffara beside Qaza and Istighfaar. Kaffara for every day of broken or deliberately missed fast is feeding sixty poor believers. Feeding means giving them one meal of food or at least 750 grams of wheat or rice or any food item.

If broke the fast  with out knowing that it is obligatory on you to fast, then just Qaza of the fast is enough.

Wassalam.

No.
Obligatory Qadha prayer must be performed as Qadha without mixing it with Nafila.

Wassalam.

If you missed fasting few days in the month of Ramadan, due to your menstrual period or due to traveling, you just need to keep Qadha fast for every missed day and there is no Kaffara of feeding sixty poor believers. Kaffara is obligatory on those who deliberately leave fasting not because of illness or menstrual period, or traveling.

Wassalam.

1.Your Night Prayer (Salat Al-Layl) is valid even if time of Fajr starts while you are still praying Night Prayer.

2.Night Prayer can be performed as Qadha and it is recommended for those who missed it to perform it as Qadha any time during day or night.

3. Last verse of Sura Al-Kahf has been mentioned in our books to be recited to wake up easily قُلْ إِنَّمَا أَنَا بَشَرٌ مِّثْلُكُمْ يُوحَىٰ إِلَيَّ أَنَّمَا إِلَٰهُكُمْ إِلَٰهٌ وَاحِدٌ ۖ فَمَن كَانَ يَرْجُو لِقَاءَ رَبِّهِ فَلْيَعْمَلْ عَمَلًا صَالِحًا وَلَا يُشْرِكْ بِعِبَادَةِ رَبِّهِ أَحَدًا
الكهف ١٨ | الآية: ١١٠]Sura 18, verse 110.

Wassalam.

When Ghusl is not possible, Tayammum must be performed to perform the obligatory Prayer within its time. Tayammum can be performed on any material of earth e.g. dry soil. Sand, stones, dust, etc. Wudhu does not suffice when Ghusl is not possible, but Tayammum is the only alternative.

Wassalam.

Yes, Qaza of Salatul Ayat is obligatory just like any other missed obligatory Prayer.

Wassalam.

Just to know in your heart that you are performing Qadha of the specific missed Prayer, for the sake of Allah (SWT).

'It is Makrouh (Disliked) to say your intention in your tongue. Intention is only in the heart in all worships. Only in Hajj and Umra rituals, it will be recommended to pronounce your intention.

Wassalam.

You don't need to repeat the Prayer as you prayed as Qadha, thinking that time has already gone. 

Wassalam.

The time of Zohr and Asr Prayer ends on the sunset.

Wassalam.