Newbie questions

[tj5...@tutanota.com]

Just starting to use Gitit, it looks nice, and I like the git repo backed idea. Thanks for providing this product. A few questions:

I installed gitit version  0.12.1 -plugins through apt-get in Debian stretch/sid. After editing a few pages, pressing export button, the web front end throws error

    Happstack 7.4.5

    Something went wrong here
    Internal server error
    Everything has stopped

    The error was "ExitFailure 97"

But there is no error loged in gitit.log file. How can I fix this? 

And how do clone the entire wiki? Copying the entire folder, which include dirs such as gitit-users,  static,  templates, and  wikidata, to another place would be enough?

I read there is preview function in github page, and PR, that looks like closed. But I don't find any way to use that function after installation. How can I enable it?

Thanks.