PAC file configuration for different locations

Hi,

Currently I am doing an Exchange migration project.

The organization has 1300 users in which 200 are Laptop users. The Laptop users will be travel from one Development Center to another. The users will be using the laptop connected to the internet in different DC's and also in their home.

My question is

1. How to configure PAC(Proxy Auto-Config) file for this scenario?
2. How and where to deploy the PAC file?
3. Is there any settings the user has to change when switching between different DC's and also switching between office and home?

Thanks,

Arun V