1996 BMW 740 AC Heater Control Valve

Yes it could be it could be a hose or a gasket or? What I would do is take it to a shop and have them do a pressure test (unless you can borrow one) on the radiator and show you where the leak is. What this does is puts pressure on the radiator (like the radiator cap does) without it running so you can find the leak safely as this can be done when the engine is cold. The low coolant is probably why you don't have heat you are loosing it to fast for the heater to stay full of warm coolant. Let me know what you find and we will take it from there.