These are two different entities. Its like asking how much water will flow with pressure. With the following formula W = Amps x Volts you can see the relationship they have with each other, the end product resulting in Watts.
As many as you want without exceeding the 100amps. You could have 100 circuits if all you have is a single 100watt light on each circuit.
100amps
Starter draw is typically under 100amps. The battery has to be in good enough shape to take the 150 amp (fuel injection, pump, and ignition) draw plus not allow a voltage drop below 10 volts. Coils don't really fire well at lower voltages if at all.
100amps
45 volts
1000
230 Volts
1.55 volts
0.016 volt
Zero volts.
4160 volts
230 volts