Carrying and burying the deceased

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?

Q: Is there any specific dua while carrying the janazah. Many times, we find people reading the shahadatain. Is it correct?

Q: Is it necessary to walk with the janaazah for a distance before burial?

Q: People who accompany the funeral and wait for the deceased to be buried in the grave yard what should they recite, is there any specific dua mentioned in hadeeth?

Q: After placing body of the deceased in the grave female or male does the kafan need to be opened up from the head side and the face of the deceased have to be uncovered?

Q: Is there any virtue reported in the Qur'an and Hadith in regard to placing a piece of the Ka'bah Shareef cloth in the kafan of the deceased or in the grave when burying the deceased?

Q: Must an amputated limb be washed and buried or only buried?

Q: Is it permissible for the husband to bury his wife?

Q: A Christian official wants to know: "Why do muslims want a seperate graveyard? Why can't they be buried with the rest of the people?