You can rotate the labels on the x-axis through the RotationAngle property in the LabelsApperance tag inside XAxis. Note that they will be centered in the space allocated for the given category (e.g. if there are three series, for example, the center of the label rectangle will be below the middle series column). You can see that in the demo you linked - expland the XAxis configurator and change the Labels Rotation Angl value. You can run it locally so you can set longer text for the x-axis categories.
So, what I would advise is that you have only one series and create the x-axis labels as required - you can databind the labels to a given column in your datasource that will hold the strings (e.g. United states, Russia, Japan,...). Another column can hold the respective values for each country on each row so you can databind the series to that column. If you cannot databind your chart you can create the items for both the x-axis and the series programmatically and set the desired string and value to them.
On changing the line series - I am sorry to say that this is not possible at the moment. This request is logged here
, so you can monitor, vote and comment on the feature.
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