Is there any best practice/guidelines available for using Code Contracts, Pex and Fake framework? Not able to find something concrete available with all 3 combined.
PEX site provides a bunch of documentation for using PEX and Code Contracts.
Your entry point probably will be Getting Started With Microsoft Code Contracts and Pex .
They also have good Moles documentation Microsoft Moles Reference Manual
Martin Angler has a great introductory article on Code Contracts & Pex: Assertions and Assumptions
There are also good workshops on this topic: