Father's property partion

My father passed away in 2008, with out any will, left one residential house in Delhi, one house in village (u.p.) and agriculture land in village, one another house in Delhi is in mother's name, she is alive & never work to earn till today, My father bought that house in her name with duly permission from his employer i.e. M.C.D, Now my mother refuse to do partition of this property, and claim to only heirs of her husband's property and threatening me to vacate the house, and to give whole property to my younger brother. we are 2 sister and two brothers , all married, My questions are : 1-How can i get my rights in property ? 2-How much share i have as per law ? 3-How the agriculture land divided ? 4-Are mother can give whole property to any one ? 5-Can i file legal suit to get my share just now, the value of father's name house is 1 crore and mother's house is about 1.5 crore, and where to file the suit and how much it will cost..