1. If the land in question was the self acquired property of your grand father i.e it was purchased by your grand father from out of his own sources of income the land passed on equally to his widow and your father after his demise. You have not mentioned whether your grand mother is alive or not and also whether she predeceased your grand father. If she is alive then your father is the owner to the extent of 50% of the land, the remaining 50% being owned by your grand mother. If your grand mother is dead your father is the owner of the entire land. He is at liberty to give the land absolutely or to the extent of 50% (if your grand mother is alive) to you by making a gift deed in your favour. Alternatively, he can make a will in your favour. If your father does not make a will or gift in your favour during his life time then the property would pass on to you, your mother and brother equally after his life time.
2. Your grand father's brothers have no share in his property.
3. As regards the property purchased by your father in your mother's name, your mother is the absolute owner thereof, as such she can give the same by will or gift to any one she desires. Neither you nor your brother can claim a share therein during the life time of your mother.