Hi Kai, and welcome to the forum.
Excel comments can't be plotted on a chart that I'm aware. If the comments were put in cells, and you could make them either the series or category name, then you could attach those as data labels.
If I hear you correctly on the plotting vertically vs horizontally, I think all you'd need to do is switch your rows/columns in the chart. Not sure what version of Excel you're using, but in 2007/2010 you can do this by selecting the chart, then on the Chart Tools-->Design tab choose "Switch Row/Column"