ESD inside Integrated Circuits
Regarding the second question - each actual ESD strike is random. In order to make it easier to test, there are standards that specify certain conditions eg HBM (human body model).
Since an ESD event is a discharge, there’s a very fast change of voltage and current, so the actual current that flows is rather complex due to inductance, capacitance and resistance. There’s also flashover that affects the actual behaviour.  The challenge of solving ESD problems is understanding where it comes into your circuit, where it leaves and what happens in between. In many cases resistors cease to exist electrically  as the arc flashes over them.