Miscellaneous masaail of Janaazah

Q:

1. Please let me know if installing a gravestone with the name of the deceased inscribed on it for the purpose of identification is Jaiz? I am told that the Prophet (Sallallahu Alayhi Wasallam) had put a gravestone on the graves of his son Ibrahim (Alayhis Salaam) and also a Sahabi Uthmaan bin Mazoon. Even today we notice gravestones in many of the graves at jannatul Baqi. 
2. Is it compulsory to reuse a grave inspite of sufficient vacant space being available in the graveyard? If required after how long can a grave be reused?

Q: Does a husband become a 'ghair mahram' of his wife when she dies due to which he cannot see her face?

Q: How does the body become najis after death that make the ghusl farz?

Q: Please tell me the steps in sequence of those responsible for the funeral expenses in the case where the mayyit cannot afford it?

Q:

1. Which people can become the wali of the mayyit and what is the sequence between them?
2. Which people are most worthy of performing the Janaazah Salaah in a non-Islamic country and what is the sequence between them?

Q:

1. Which shahadat should be given preference for the talqeen of the muhtadar, the first shahadat or the shahadatain.
2. From which side the qabr must be close with the plank for man and woman. The head side or the leg side.
3. In the niyyat of the janazah salaah, is it necessary for the muqtadis say within themselves “behind this imam”.
4. We used to walk in between the qabr with the shoes, I came across the Hadith discouraging to walk with the shoes. What should we do?
5. Can we eat the fruits and take home the flowers of the qabarastan. If not, what should be done especially with the fruits? Let it get rotten on the trees?
6. What the Shariah says about of planting on the qabr, especially after the burial. The flowers most of the time are taken from another qabr. Sometimes we find big big plants on the qabr. Should we keep the qabr completely neat at all times?

Q: I would like to know whether the deceased (dead body) still feels any sort of pain if mishandled - intentionally or accidentally. Externally it is seen that it has no soul, no ability to talk, see or express any feelings. Does it mean we can keep the dead body into a freezer (for 1, 2 or even 3 days) so that the relatives (specially sons/daughters, spouse) can arrive from a foreign/distant land to have the last view of the deceased? What is the Shariah Rulings regarding this? Whoever are in charge of all those activities like keeping the dead body into a freezer, delaying the Janaza and burial - will they be regarded as the Sinners and accountable in the eyes of Allah?

Q: By keeping a photo of a person who has passed away have any effect on the deceased, like any punishment on the deceased etc?