The speed sensor is there to detect when you overspeed, and when you are on 'overrun', where it can turn off the injectors to save fuel and improve emmisions.

Stalling at the lights is caused by faulty AAC valve, dirty Idle air passages, or coolant temperature sensor needs replacing. The 2 pin temp sensor, not the spade terminal one.

All factory ca18 turbos have the dropping resistor. Yes you could get some 375cc high impedance injectors and not run the dropping resistor. I run 550cc rx7 series5 injectors on my CA18 which are high impedance. No dropping resistor required...but running the 550cc injectors will only work with ECU mods or aftermarket replacement.

I'm not sure why your balls are involved in the wiring.