You can generate those from Visual Studio (Tools / Create Guid).
Create GUID in Visual Studio 2008/[
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1) No it cannot be anything. It must be unique globally).
2) It should be easy to find example on the web. The tool allows to create in a variety of format.
3) The value is generated according to some rule to ensure uniqueness.
More links:
Globally Unique Identifier[
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Guid Structure (.NET)[
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You can also generate Guids online :
Google search[
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