I don't know the drain and fill amount. But mine needed some fluid. It took nearly 95% of the 1qt found at Auto Zone. How empty mine was, wasn't known. So buy 3 qt just in case and take back what wasn't needed.
Just fill it up until it comes out at the fill hole. Also buy a tube that will fit the top of the bottle's nipple once you cut it. Cut just enough where fluid will come out, but not too much where the tube won't fit/stay on during the process.