NOC is not required anymore for aircraft like 737
Read this CAR very carefully and thoroughly
http://www.dgca.nic.in/cars/D7B-B19.pdf
Please make sure your RT , FRTOL and medical are also valid prior to and during the period of the rating
I dont believe you need a valid IR for type rating since you will be getting a new one anyway, but someone who has done their type recently should be able to help there
The DGCA now requires the TRTO to send some documents directly to them . I strongly suggest you keep a scanned copy of all documents the TRTO sends directly to the DGCA as they are notorious for losing documents
When the TRTO sends the documents directly to the DGCA make sure they include your DTL Section file number on the address of the envelope so that it reaches the correct department without them having to open the envelope first