Are you intimately familiar with the inner workings of your heatpump? Nearly all heatpumps in a cold climate have backup heat built in and it would automatically switch to backup when it gets too cold outside. -30C is well into the too cold category for it to function as a heatpump alone
Lol wildly exaggerated. Largest height difference on Earth’s surface is 13 miles (including underwater) vs. the 8,000 mile diameter. To quote NDGT, “The Earth is smoother than a cue ball”