Re the tanged washer - To keep the road wheel torsion away from the hub nut and safeguard the nut from undoing. If a bearing seizes and the inner rotates, any side load from cornering would apply a turning moment to the fictionally locked washer and nut (if there was no tang). This could undo the nut. All that would then prevent the wheel from coming off would be a meagre soft steel split pin that could be sheared.
