What is the amount of insurance I can choose?

You can choose any insurance amount from $15,000 USD till $1 million USD. 
The insurance amount will depend on your assessment of risk for the time and country you plan to go to. For example, the cost of medical expenses is high in countries like Japan and the USA so you should ensure that you get yourself covered accordingly for these countries.

Note: If your insurance provider is ICICI Lombard, you can choose any insurance amount from $15,000 to $5,00,000.