I don't know what else is on the circuit with your Dishwasher, but it is possible that you have a defective circuit breaker, or corroded wiring at the circuit breaker or at the dishwasher. Maybe too many gadgets on he same circuit and you are tripping the breaker. The dishwasher may have an internal circuit breaker that needs replacing. some thing to think about.
Spray arm first, then the split white ring on top and the top screw. There will be around 1 1/8" gap (the spray arm wobbles when it's not running). You're doing it correctly.
It sounds like you have a build up of debris in the bottom where the drain is. You can take apart the bottom and clear out all of the accumulation. Put it back together and it should drain fine. You could also check your drain hose and replace if necessary.