The Arabic word qada (قُضِي) means literally "carrying out or fulfilling". In Islamic jurisprudence it refers to fulfilling or completing those duties that one may have missed due to some reason or other.
You should make up the missed prayers and you can also personally ask Allah for forgiveness during du'a.
No, as far as you are still alive. You must perform your own Qadha as soon as you can during your life. If a person passes away before completing all his Qadha prayers and fast and Hajj, some one else will be allowed to perform the Qadha on his behalf whether with payment or with out payment.
You can ask or pay during your life to some one to perform Qadha after your death but this will not free you from the responsibility of the Qadha until you perform it yourself during your life. If you die before performing your own Qadha worship, you have to suffer a lot till Qadha is completed after your death.
Yes, she has to perform Qadha for Morning Prayer which she missed after being clear from the menstruation. She should have performed Tayammum and prayed on the time of Morning Prayer if Ghusl was not possible.
If you do not know the exact number of Qadha prayers on you, you should have an idea about minimum and maximum numbers. The obligatory Qadha will be the minimum which you are sure about, and the precaution is more than that.
Only the obligatory parts in reciting and actions with out recommended reciting or actions.
The fastest way to perform the Qadha prayers is to recite the obligatory parts of Salah only with out any recommended part. Starting the Qadha prayer with intention in the heart only and no Azaan and no Iqamah but only Takbiratul Ehram then reciting Sura Al-Hamd and short Sura, then Rokoo' with Subhana Rabbial Adheem, then Sojood with Subhana Rabbial A'la.
Yes, because Salah is invalid before its time. If you are sure that the whole Salah was before the time, not part of it, then it should be repeated. If part of the Salah was before and part inside the time then many Ulama say that it can be valid.
If the eldest son is unable for health reasons to keep the Qadha fast of his deceased father, any of his brothers or sisters can do that. If he has no brothers or sisters and has no money to pay for someone to do that, he should recite Estighfaar.
Thank you for your question. In normal circumstances, the magrib prayer becomes qadah at midnight (according to Ayatullah's Sistani's fatawa), so there is no reason to make the intention of qadah at 10pm unless that was past midnight.
May you always be successful
It is obligatory to make up, means to perform the Qadha, of every
missed obligatory prayer. The easiest way to perform all the Qadha prayers if the
period is long, is to perform only the Wajib parts of the Salaah. Only
the Wajib parts of the Salaah with out the recommended parts will make the Qadha easier. And it is good to make a timetable every day and night to spend some time in
performing of the Qadha and that also will make it easy Insha Allah.
There is a Qadha' and Kaffara for every day of missed fasting of the Month of Ramadhan. The Kaffara is either fasting two consequent months or feeding sixty poor believers.
Qadha must be done as soon as possible.