Hi Thorsten,
it would be easier IMHO to display your status info at the top of the console and nail the input line to or near the bottom. In 4DOS times there were very elaborate ANSI prompt sequences to do just that.
The advantage is that you will find your input line always at the same position, you can use CLS to paint the whole console the color you like, you'll see the input and output of preceding commands, you won't overwrite your status line (though it may scroll off for very long inputs).