what happens in 1ohm VS. 4ohm?

Your right on track. Because the amps load is lower, it requires more current from your electrical system. Using Ohm's law (V=IR) I=V/R. If you 1/4 the resistance (4 ohm to 1 ohm) the amp needs 4x the current to maintain the same voltage. But since no amp is 100% efficient, and depending on the amplifiers voltage regualtion it's internal power supply will run out of juice alot faster, thus putting more strain on your car's electrical system at peak output. Adding a second battery or stiffening capacitor to the electrical system will help support the amplifiers demands during these transients.

Voltage up, Amperage down. Amperage up, Voltage down. This is very simplified and I'm sure someone here can give you the math. When your electrical system is under load your voltage will drop So the alternator and battery must supply more current to supply the load. Running an amp at 1 ohm either bridged or stereo has many disadvantages. The amp is going to run very hot, the amp will be drawing maximum current, and dampening will suffer (amp's ability to control cone motion). Another side effect is the loss of headroom. (amps reserve power storage). At this point clipping becomes a big concern. Clipped power blows speakers. You are forcing the amp to give all it's got and when it has no more to give, somethings going to break. . .