Question 7
Faster to compute the list of neighbors on scaled data.
k-nearest neighbors is based on computing some distances. Features need to be normalized to contribute approximately equally to the distance computation.
Scaling the data has a negligible effect on k-nearest neighbor’s performance, but it enhances the interpretability of the model.
This is irrelevant. One could use k-nearest neighbors without normalizing the dataset and get a very similar cross-validation score.