To answer your first question, the VI is looking for an "end of line" constant (ASCII 13) which it doesn't find, so it takes the entire text and places it into the first cell. The string to num VI takes only the first line. If you replace the constant with a line feed constant (ASCII 10) it should work.
About your second question, it depends what you mean by manipulate. If I understand you correctly, the best way would be to have one graph which displays a lot of data from different sources. If you search the example finder for "graph" you should find at least one which will show you how to do this.
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