There are 4 dealerships in Kolkata for Renault. Renault Rajarhat, Renault Kolkata, Renault Kolkata South, and Renault Kolkata Central. For their locations and contact details, follow the below link - Dealers.
Renault offers the Triber with a 1.0-litre, 3-cylinder petrol engine that produces 72PS and 96Nm. For now, Renault offers only a 5-speed manual transmission option on the Triber but a 5-speed AMT will be launched in the next few months.
Yes, you can install alloy wheels in Triber, and for the driver seat with height adjusting feature we would suggest you to exchange your words with the service center people as they have a separate department for accessories. You can click on the following link to see the details of the nearest service center and selecting your city accordingly - Service Center.
For the availability, we would suggest you walk into the nearest dealership as they will be the better person to assist you because it depends on their stock book. You can click on the following link to see the details of the nearest dealership and selecting your city accordingly - Dealership.