Migrate from ClearCase to TFS

We are using ClearCase for version control and now evaluating feasibility of migrating to TFS. We need to either migrate to TFS completely or use both TFS and ClearCase and sync the source code periodically. I did not find any tools for doing the same. If anybody has any clue of a tool or option in TFS please help me with following

1. How to migrate all our source code from ClearCase to TFS

2. How to sync ClearCase source code on nightly basis with TFS. In this case everybody will be working with ClearCase. Periodically the TFS Source Control will be updated so that we can use the build and test management features of TFS.

3. How to transfer source code in TFS to clearcase periodically. This is required in a scenario where

a) All are working directly with TFS source control

b) Periodically ClearCase need to be updated to have the latest versions from TFS

Thanks