1. The property was owned by your father who did not make a will in respect thereof during his lifetime. So after his demise his widow and all his children succeeded to his house. Division can take place amicably by drawing up a deed of partition or family settlement. If your sisters are willing to give up their share then they may execute a deed of relinquishment.
2. So far as the properties in the name of your mother are concerned, she can execute a will or gift deed to transfer the properties to you and your brother.
3. Stamp duty in your case will be 4%. It cannot be avoided even in case of gift among blood relations. Registration charges will also have to be paid. Will is a better option if you wish to avoid payment of stamp duty.