This is not a plug for my firm's services, but I honestly believe you could use the services of an outsourcing adviser. Because the scope of the question is too vast and complex to be addressed in Quora format, and any attempt to provide a truthful and meaningful answer would involve a deeper understanding of the organization that is looking to offshore part of its operations.
An outsourcing adviser would also be able to connect you with the relevant vendors/ service providers at locations you would finally decide upon, help you negotiate and arrive at a comprehensive agreement (can be a bit tricky), support your transition PMO and also help you build a governance model that will continue to oversee the offshoring arrangements on an on-going basis.
The short answer to your question is that you need to formulate a IT services globalization strategy. But in a way, saying that is like re-casting your question in a different manner, and may not help much.
That being said, the following questions may provide a flavor of the kind of issues involved in formulating such a strategy, and that require detailed study and discussion (by no means a comprehensive list – just enough to give a sense):
1. Why are you considering offshoring? Is your prime driver cost or something else (e.g., access to resources/ skills/ process efficiency/ engineering quality)? Are you looking to increase development capacity or improve delivery capability? Have you built a business case to justify it? Are there any specific drivers that are time-boxed (sense of urgency)?
2. What do you want to offshore? How common or unique are the platforms/ technologies involved? Do you have issues in finding skilled technicians locally? How much of your work currently is based on waterfall type of lifecycle models versus, say, agile?
3. How important is geographical proximity and timezone compatibility? Does your organization have a global footprint – do you have offices in some of the locations you've mentioned?
4. How important is the need for scalability? What is the quantum of your initial scope and what does your ramp-up plan look like? (Orders of magnitude; exact numbers may, understandably, not be available at this stage)
5. What is your experience with outsourcing/ offshoring so far? Have you worked with service providers? If so, have you mostly entered into resource-based contracts (typically on a "Time & Materials" basis) or have you also tried "Managed Services"?
Hope this helps.