Qadha

Saying Takbir before ar after Sajda Sahw is not obligatory. Your Prayer is valid with out Takbir for Sajda Sahw.

Wassalam.

Yes, it is permissible and might help in reminding you making your Qadha prayers.

‘Wassalam.

No Muslim does not know that Prayers are obligatory on every Muslim unless he lives in the jungles where no one knows anything. You must perform your missed obligatory Prayers as Qadha.

Wassalam.

Pray Qadha of Asr first then Maghrib and Isha.

Wassalam.

If the ejaculation occurred without intending to do that, Qadha is must of that fast. Kaffara is obligatory if it was done intentionally. But how can one masturbate with out intending to do it? Was he sleeping. If he masturbates while he was awake then he has committed it intentionally. If he masturbated but his intention was not to reach to ejaculation, and ejaculation occurred with out his control, that might be possible.

Wassalam.

We must try our best to perform every Prayer within its time and never miss any Prayer as much as we can. If God firbid, Fajr Namaz is missed, we must perform its Qaza as soon as we can. There is no condition to perform Ghusl of Jum’a before performing the Qaza although Ghusl Jum’a is very great recommended Ghusl, but you can perform the Qaza of Fajr with Wudhu only or after Ghusl Jum’a if you wish but Ghusl Jum’a is not obligatory nor a condition for Qaza Namaz.

Wassalam.

No action is due on you.

Qadha fast can be broken deliberately any time before Zawaal (Midday or Dhuhr time)..

If Dhuhr time comes then it will be Haraam to break a Qadha fast.

Wassalam.

Yes. As you were born as a Muslim from Muslim parents, you must perform what you missed from the obligatory worship. You can perform the Qadha gradually as much as you can.
Wassalam.

Qaza fast is obligatory on you as soon as you can. If you become permanently ill and never able to fast, then you need to feed for every day a poor believer which is called Fidya. That is for the days missed while you are ill. For the days which you missed during your youth with out illness, you need to feed sixty poor believers for every day of missed fast.

Wassalam.

No doubt that performing Qaza prayers is obligatory and more important than recommended prayers. The reward for Qaza prayers is more than recommended prayers.
Wassalam.

Touching any Najis item including dogs or its urine etc does need Ghusl at all. You need to wash the part which touched the Najis item with water, then perform Wudhu and pray. It is a sinful act to delay performing the Prayer till it's time goes. Performing the Qadha namaz will not omit the sin of not praying within the time of the prayer.

You must perform your Namaz within its time under any circumstance.

Wassalam.