I believe it’s because currents of air rotate in the opposite direction. So to cross the equator the air would have to pass a boundary of global air currents which are going counter to the hurricane’s motion. See this picture for a reference.
No - the direction the toilet water spins depends on the small scale vortices created when you flush. The Coriolis effect is slow - it acts at a much longer time scale.
In theory, yes. However other factors such as the shape of the drain, the shape of the toilet bowl, and any small initial motion in the water, usually completely overwhelm the coriolis effect. You would only be able to observe it under extremely carefully controlled conditions: extremely still water, and a completely symmetrical toilet bowl perfected to extreme, micron precision.
For something like a toilet where water is staying into it, the force of the spray itself is all that really matters. But, for water that is still (pulling the drain on a bathtub), then yes, absolutely this is true. The spin will be the same as a hurricane (depends in hemisphere), and for the same reason.
Technically, no spinning from the Coriolis effect. Realistically, something tiny like you reaching into the water will create enough movement that you'll get it going one way or another.
Because of things like Coriolis effect and convective currents, there just aren't winds that blow across the equator, not at the scale that would blow a hurricane from one hemisphere to the other anyway.
Winds tend to blow along and away from the equator, not across it.
For ELI5, think of it this way. The earth is spinning, and at the equator it's moving really fast, like 900 mph. At the north pole, the earth isn't moving at all, so in the northern hemisphere, you can picture all land to the north of you as moving slower than you, and land to the south as moving faster than you. If you run south, it would spin you because it's moving 'sideways' faster than you are. Cross the equator and suddenly it gets slower as you run south, literally putting the brakes on your spin.
The ancient city of R'yleh is rumored to be somewhere along the equatorial line. In ancient times was known as the torrid zone, an infernal place which claimed all the lives of those that cross it. Hurricanes are a force of nature and, since no two forces of nature can overlap (like a volcano during a storm or an earthquake and a flood) the hurricane can't go where ancient ones dwell.