A1: The scholars have three opinions one opinion is you can fast on those 9 days with the intention of replacing what you missed in Ramadan only, one intention because those are two separate tasks of worship and in sha Allah you will be rewarded because of the precious days, and this is to be in the safe side. Some of the scholar allow to have the two intentions (Shafaie, Ibn Othaimain and Altoraify) allow it, they said Hadret Omar Ibn Alkhattab used to delay replacing what he missed in Ramadan to those 9 days The third opinion is from Sh AlAlbany he said it is permissible but the reward will not be the same And Allah knows best.

A2: This hadith is weak and you can recite Duaa for blessing and success for any month any time of the month. Also Hadiths mentioned specifically for the month of Rajab all of them are either weak or fabricated. Rajab is a sacred month that we should utilize with good deeds like Umrah or Sadaqah or fast some of its days (at least Monday, Thursday and or three white days). And Allah knows best.
A3: It is up to you to break your fast if you see it if any benefits, it is Likked to continue what you start it, and to do better you should accept the invitation and do not break the fast instead you make Duaa for the one invites you. And of course if you break your fast you will be rewarded only for your intention but if you fast you will be rewarded for the intention and fasting that day.
A4: You have to know that the father or the mother are the responsibility of the son or daughter, it is an obligation to provide for the parents, having said that, if that debt was because they did not take care of the parents and the children neglect and did not provide for the parents which made the parents have that debt then it is the duties of the children to pay it off not from the Zakah, but if the reason for the debt was something else ie luxuries things then they can pay their father’s debt if he can not afford to pay it, and it is not obligatory on the son or the daughter ( because the father is from the debtors which mentioned in the verse of Zakah والغارمين). And Allah knows best.
A5:Prayers are prescribed by the prophet ﷺ and it should be performed as it was prescribed, like making Zikr one time in certain places and few times in other places, but if you repeat the Zikr few times in the part of the prayer which supposed to be one time, will not invalidate your prayer because the repetition of the Zikr will not affect the formation of the prayer. My intake on your question I prefer you do not repeat the Zikr rather you saying it slowly, it will be better. It is also permissible to be silent after you do your Zikr, waiting for the Imam to continue, this will not affect your prayer or invalidate it. And Allah knows best.

A6: Aqiqah is authenticated Sunnah as per the majority of the scholars. It is time will be on the seventh or fourteenth or twenty one days then any time. For the boy you slaughter two sheep ( also it could be one sheep) and for the girl one is prescribed. You can cook the meet ( majority of the scholars) or give it without cooking it is permissible. The majority of the scholars agreed upon that Aqiqah could be from either camels or cows or sheep or goats for each should have reached a specific age as follow: Cows or buffalo should be full year at least, if it is two years going to third years or complete three years it is ok. Sheep, it should be six months old. Goat it should be one year old. Camel should be five years old Also the animal should not have any disfiguration. Lastly some scholars said one cow could be for seven children like Qurbani and some said it is only for one. Aqeeqah you could give it as a gift, or you can eat from it or you can store some of it or you can give it as charity all this are permitted. The only thing is you cannot sell it. And Allah knows best.

A7: Yes you can ask The Almighty to grant you Barakah (blessing ) in your age and extend it to serve Him. That is allowed. Our prophet ﷺ made that Duaa for Hadret Anas (may Allah be pleased with him), and he died about 103 years old. Also you should believe that your age, your provision, your happiness and your deeds being written while you were in your mother’s womb and the best amongst us is the one utilize his/her time to the best of his/her ability and follow this beautiful verse: (لا يكلف الله نفساً إلا وسعها) And Allah knows best.

A8: this hadith is weak and you can recite Duaa for blessing and success for any month any time of the month. Also Hadiths mentioned specifically for the month of Rajab all of them are either weak or fabricated. Rajab is a sacred month that we should utilize with good deeds like Umrah or Sadaqah or fast some of its days (at least Monday, Thursday and or three white days). And Allah knows best.

A9: I stated (briefly) that both terms have different ruling, Covenant is obligatory to fulfill due to the agreement between the two parties and if you do not then certain penalties will take place, example for this a contract with two parties with certain conditions. Allah, The Almighty stated that in the beginning of Surat AlMaàedah #5 verse 1. Promising is liked by the scholars to be fulfilled but if you can’t there is no penalty or punishment except ill feeling against you, example for this is when you promise your children something. my advice if you promise say إن شاء الله and if you can’t fulfill it, just sweet apology will solve the problem. Furthermore, some people uses both terms the same, in this case they will have same ruling. And Allah knows best.