Do I understand this request correctly: It should enable work-wrap in the control but upon clicking the Commit button, it should insert line-endings automatically for too-long lines?

We don't have plans to support special formats out of the box, but rather support external converter tools, because this would be much more flexible and does not introduce special cases.

Do you know a good command line tool to convert the binary .docx file to a text file?

What platform you are using? At least on Windows with http(s) killing the Git process (using the limited means of Java) lets the forked git-*.exe running. We also are not sure whether killing a Git process always is safe for the repository structure.