83 240D - Need tips for heater core replacment
 

I have a sweet coolant smell when the fan is running and a slow coolant loss. I have to assume the heater core needs attention. Does anyone have any tips for verifying this without removing the dash, or possible other problems that may cause a slow leak inside the car?

Assuming the dash needs to be removed, how big a job is it, and does the AC system need to be opened?

Any help is appreciated.