heat and window defog

You may have a clogged heater core. Take the vehicle into your local service center and have them back flush the system. If this doesn't work you may have to replace the unit.

I recommend you take your car to a specialist in the area. BMW's come up to temperature very quickly sounds to me like you have a blockage in the cooling system. The shop should check the thermostat, heater control valve, and water hoses going into the heater control valve also.