Procedure for marrying Turkish national in India

I am Indian passport holder, currently deputed to China on work assignment (having working permit but no resident status) & engaged to a Turkish passport holder. Request information on the following: 1. Steps required for accomplishing civil marriage with the aforementioned Turkish passport holder in India (would appreciate details on whom to approach (lawyer or registrar) & which cities can perform the marriage in court of law (I come from Kolkata, West Bengal). 2. Documents required for the Turkish passport holder to carry from Turkey & also documents required to be produced by me 3. Minimum & maximum time required for the Turkish passport holder to stay in India to accomplish the marriage. (would appreciate details on whether and which type of Visa to be applied therefore) 4. Minimum & Maximum time required for me to be present in India to accomplish the marriage (since I am stationed in China currently on premise of work) 5. Except the requirement of physically being present at the time of signing of both parties in the court, can the whole process be eased out if I hire a lawyer or is it that all steps are to be mandatorily required to be done in person by the person getting married. 6. Any recommendations of law firms or consultants in Kolkata, India who can assist me with their paid professional services 7. Is civil marriage accomplishment means the marriage is registered legally in India? Or any additional steps to be followed? 8. Would the witnesses required from both parties mandatorily? i.e. atleast one from each country Turkey & India? 9. Any approximate cost & overall time estimates for the above will be much appreciated.