Total Commander

I'm using Android TC 3.42 to mount a WebDav directory.

Is it possible to create new files on WebDav?
I know it's possible on normal directories with long-tapping on "..", but for WebDav directories I don't see such an option.

No, unfortunately not - you would have to create the file locally and then upload it. Afterwards, you can always edit it via long tap - download+edit.