1- No that is not true. You can pray Nafilah even it you have Qadha on youZ
2- You can pray Salat al Layl even if you have Qadha prayers.
3- You cannot combine between a Wajeb Qadha and Nafilah prayer. Yes you can pray the Qadha prayer and then ask Allah to grant you the reward of a Nafilah prayer as well.
4- Since the age you are certain you became Balegh. Let’s see you are not sure whether you became Balegh at 12 or 13, you can start from 13.
5- Yes it is obligatory. Estimate on average how many eclipses/earthquakes have happened in your area in the last few decades.
6- No just the daily prayers and the Ayaat prayer.
7- You make them up as Qasr.
8- Same as prayer. From the time you are certain you became balegh.
9- You make up one day for each missed day. So that’s 30 days for each year. Now if you knew fasting was wajeb and you just ignored it, you also have to pay a Kaffara of feeding 60 poor people (the equivalent of 750 grams of wheat) per each day missed.
10- It is not an option. If you are traveling and not staying in a place for more than ten days, you must pray Qasr and you must break your fast.
11- No when traveling you cannot make up Qadha fasts.
12- You would pray full and fast if you travel at least 10 or more days each month.