Thank you for the opportunity to help you with your question!
This is the order in which everything occurs
potassium channels are what polarize the cell and if these are blocked the neuron is inhibited. It's chemically regulated because ACh, a chemical, affects it.
potassium flows out of the cell during repolarization so increasing potassium outside the cell would cause hyperpolarizatoin. It also affects the magnitude of the potential because you have made the extracellular potassium concentration closer to the inner concentration.
The positive ions flow out of the cell making the inside more negative.
Please let me know if you need any clarification. I'm always happy to answer your questions.