Carrying and burying the deceased

Q: Can a son in-law go in the grave to bury the mother in-law?

Q: Can a mother and child who passed away together in an accident be buried in one grave?

Q: What will be the role of a husband after the death of his wife? Can he give shoulder to the Mayyit?

Q:  Is it better to raise the graves a little like that of a camels hump or better to flatten it like how its done in Jannatul Baqee?

Q: 

1. Should one sprinkle water on the qabr after burial? Many people do so. What is the shar'ee hukm?
2. If plants grow on grave should they be cut?
3. Should one put a twig on the qabr?
4. People look at the mayats face and delay the burial. What should be done?
5. Is there any Hadith regarding recitation of the first and last ruku of Surah baqarah after burial and also what is the hukm of dua in congregation after burial?

Q: Last year my father passed away in Pakistan. Because of the rain, my father's grave opened. Can we put soil in the grave or is there another solution? Please guide us.

Q: Covering the janazah of a woman, how did it start?

Q: Is there any authentic hadith from the books of hadith about the forty steps for each person to carry the janazah?

Q: The children who die while in the wombs. Is it necessary to bury them in the qabrastan or anywhere else (for example; garden, backyard etc)?

Q:

1. Can we allow the non muslim to participate in the funeral rites of a muslim?
2. Is it Mustahab to place a green twig on the graves?
3. Is there permissibility to plant on the graves?
4. A pregnant woman dies and it is not known whether the child in the womb is alive or not. What should be done in this case?
5. Is the qamees of a male similar to the female? Is the hair of a female divided into two parts and place on the qamees?