Wife separated from 2 and 1/2 years.

1. My wife has left my home along with 2 children(Daughter 9 years & Son 7 years) on September 18,2016 to her parents house at around 9:00 pm. Then she came back on 3rd day in my absence but in the presence of my father and took some clothes and again gone back. Then after 5 days she came along with her Masi and Maami in the absence of mine and my father and took away all the essentials from the house like jewelry, Bank FD's and some other important documents. While she was leaving my father and taayaji came to home, when tried to stop them she called up police and took the things with her. 2. After that incidence next very day her 2 cousin brother's visited to my father and taayaji and assured for reconciliation, but nothing happened. Around after 1 month me along with my taayaji went to my in laws house to settle up the things, but nothing got materialized. The same been tried 5-6 times but nothing happened and she refused to stay along with me as of under the influence of her parents and relatives. 2 times they all abused us very badly and tried to do man handling with us. 3. After lot of requests, almost begging she made me meet my children for around 4 times till now. From past 6 months she is not allowing me to even talk to my children. She has blocked my number, Facebook, Whats App from last 2 years. 4. She being a teacher*my children also study in the same school), I am not been able to meet my children even in school premises as the Principal also denied stating that children are coming with her so she cant allow me to visit my children until and unless my wife permits. 5. About myself, I work in an MNC and my monthly gross income is 1lac/month. I live alone with my father, aged 70 years. I had a house where I am living with my father. My wife is a school teacher and earns Rs.55,000 per month. My wife lives in a rented house with her parents. I am having one video recording where my wife's relatives have abused me and my taayaji and tried to man handle us. Also hundreds of messages sent to her to come back to me and make me meet/talk to my children. Till date no any police complaints or litigations from either side. Lastly, I must say the major reasons for whole mess been created is my in laws interference, especially her mother's. My wife being the only child to my in laws wants that she should be with them almost everyday. QUESTIONS: 1. Can school principal deny to visit my children at school? What should I do so that I can meet my children. 2. On what ground should I file a divorce? 3. How much maintenance should I expect court will order me to give her considering my wife also earns? 4. What are the fair chances of mine to get child custody? 5. My wife's right to my property(house where I am living along with my retired father). Her rights to my ancestoral property which is on my father's name.