Kopar east chawl is legal or ilegal

Respected Sir, I am intending to purchase a room in NEWLY BUILT CHAWL at KOPAR (EAST). Construction is done by 4 persons in partnership by purchasing land from another person. On my inquiry, i have been informed that this area is covered under KDMC and copy of 7-12 produced before me. Now my query is: 1. What document I should check to confirm whether it is a legal or illegal construction? 2. From where and how to inquire about any future projects on that place by govt? 3. What type of another precautions to be taken before finalizing the deal? Your immediate and appropriate response is highly expected and will be appreciated... Thanks and regards