Is A Will Valid, When Not registered and not witnessed?

Hello Sir, I Am Sagar. I HAve One Question About Will.

my grand-father's property is in Ahmedabad, Gujarat State OF India.

MY Grand-Father Made A Will in the Year jan 2005, And HE died in feb 2005. The will Is not registerd, As well as it is not having any witness.When He Died, I was Not of 18 years(my D.O.B.=12/10/1989).
But now at present i am 21 years old.

In Will, He has told to distribute his property(Bungalow) equally among three partners: One ME Itself, And the Other Two are my Aunts(Fias:Father's Sisters.)

Also, it is clearly mentioned in the will that until his wife(My grand-mother) is living, his property cannot be sold.

It is clearly mentioned about her(My Grandmother ) that she will live in that property until her death. Then And Then Only, I And MY Two Fias Can Sell the property.Also, It is Clearly mentioned that the property can be sold only and only if all the three partners are combiningly agreed with the selling of property.

Meanwhile, Due to the Severe satge of cancer, MY father Died On 25/07/2009.

At present I, my mother(widow: 49 years old), my younger sister(14 years) are residing at the above mentioned propety with my grandmother.

my grand-father had three wives.The one residing with us is the third and last wife of my grandfather and is the step mother of my father, and also of the two Fias. the Second Wife was the mother of my two fias, but she died on 22/02/1973. Also She Was the step mother of my father. The First and the Legal wife of my Grandfather is still living with his one son and one daughter, apart from us.She is the real mother of my father. And both her children are my fathers real brother and sister. They are not living with my father since 1964.

MY grandfather has clearly mentioned in his will, that his son and daughter of his first and legal wife cannot claim his property. and he does not consider them as his children. Also, my grandfather has clearly mentioned that the descendants of the son and daughter of his first and legal wife, cannot claim his property.

MY grandfather has not given divorce to his  first wife. and thats why she had filed a case on my grandfather in 1964 for "the cost of livelihood"(khadha-khoraki).the judgement of this case arrived in the year april/may 1996.

the judgement contained the contract that my grandfather has to pay 500 rs. per month up to his death. and he did so. also he paid approx. rs. 65,000 from the year 1964-1996 to his legal wife, according to the order from court.

in that judgement my grandfather had said that he is having only onle wife(legal one), and three children(of the legal wife)..and the lady living with him is a servant.

Under these Circumstances:: MY questions are:-

1. Is the Will Made By my Grand-father which is not registered and which is not having any witness Valid?

2.     We do not have any house(immovable property), where we can live, other than this. and my two aunts have her own houses. and both of them are living in their own houses. But they are torturing us to sell this Property, inspite that my grand-mother is living at present. i am a student at present and my mother is only an earning member of my family.my grand-mother who is living with us at present ios very soft-spoken and cant oppose to my fias. is it possible for my Fias To sell this property without my agreement, even if my grandmother gets convinced?

3.     Is my Mother(Widow at present), A heir of this property According to the Succession Laws?
 

4.     Can MY uncle and Aunt(Son and Daughter of the Legal wife of my Grandfather) claimThis Property?

5.     According to the Will of my Grandfather, if I dont agree with my Fias to sell this Property Till my Grandmother is alive, can they lock one-one Room Each in this Bungalow(property), in which we are living at present?? It's Because They are torturing us to sell the property urgently, else they frighten us that they can give one-one room each on rent, or even they can lock the rooms., inspite of my grandmother and my family living in that bungalow. Also, i HAve never denied them(my Fias) for their living in this bungalow.But they want to sell this property urgently, and hence are harassing us mentally. What would be the Solution in this Case.

6.     Inspite of my grandmother(Pensioner of my Grandfather) living with us, My Younger fia had kept the atm card, cheque book and pass-book of my grandmother of her pension account. and also she is not giving her pension fully and time-to-time. my grandmother is a soft-spoken lady and is not able to confront her. What to do in such a case legally?

7.     Can MY original Grandmother(First And legal wife of my grandfather)  still Claim The Pension as a pensioner of my grandfather,As a legal widow?

I request you all to reply me with the possible solutions. My Email I.D. is :-  tangyss1217@gmail.com

Thanking you.