Wheels are a prestressed linear superposition of overall tension and a compressive load at the bottom. Generally, you'll see ~4 spokes at the bottom of the wheel relaxing to take the vertical load. (in a properly built wheel)

This is due to rims not being completely rigid, but being a somewhat flexible beam. Rims are nowhere near rigid enough to do the "hang from the top" thing.

Spokes will break at the elbow, but generally due to fatigue, which is made much worse when there are stress reversals. Fatigue is when cyclic loads cause small imperfections to grow into cracks, and eventually failure. If you have stress reversals under rolling loads (where the stress goes from tension to compression, anywhere in the spoke elbow) you should expect to see spike failures in ~1000 miles. A stress reversal doesn't necessarily mean that a spoke is slack, because there are some interesting stress patterns in the elbow in poorly built wheels.