Supplications

When a person makes Du’ah for another Muslim so that Allah would forgive them, Allah accepts this Du’ah. If your question is whether this dead person knows about this Du’ah or not, he most likely does not. And Allah knows best

No, it is best to vary from one to the other but not to say them all at once. And Allah knows best

It is permissible to recite verses of the Quran in the Ruku or Sujood as this is not reciting the Quran but it is Du’ah. It is like reciting Ayatul Kursi before going to bed while a person is in the state of sexual impurity. And Allah knows best

Yes you can providing you are doing this after you have said the mandatory thikr. And Allah knows best

It is recommended that you do it while in your prostration and also after the last Tasha’hud; before offering salam at the very end of your prayers. If you want to make general Du’ah, you also can do that any time of the day but don’t make it a habit to make it after prayer. […]

If there is no mentioning of Jesus or his mother and only Allah is mentioned, this is permissible. And Allah knows best

You have to say it And Allah knows best

Yes it is permissible.

Praise be to Allaah The dhikr after salaah referred to in the question has been reported in a hadeeth reported by Abu Hurayrah from the Messenger of Allaah (peace and blessings of Allaah be upon him): “Whoever glorifies Allaah (says Subhaan Allaah) thirty-three times immediately after each prayer, and praises Allaah (says Al-hamdu Lillaah) thirty-three […]

Yes,you can if this is what you hopes for.