My questions are:

1) Is there a plan to open source or release a public version of the binaries for client and server? If no, does GPL licensing not force them?

2) do they handle per file permissions or is their codebase completely open to all contributors?

3) how much performance benefits do they actually get? (with the details of the test repository)

I know Microsoft has GVFS but I'm guessing they have multiple repositories, so permissioning is probably not an issue they have tried to solve. The github.com repo doesn't have code for permissions