aquascape

On my 2007 transit connect with 105k on it, not always but sometimes after a long journey I check the coolant level when I get home and it is fine but by the next morning it is half empty. It never loses any water when in use and if definitely doesn't leak onto the floor. If drives lovely. Any ideas?

How do I remove the stereo from a 2011 model transit connect, it is the new oval shaped unit?