Essentially, PDF is an end-of-the-line format - designed for printing a document on an arbitrary medium, with the minimum distortions.
If you want something that is editable, you have to pay Adobe for the privilege. That also will only be useful if the document is not locked. You are then in the game of taking a snapshot of the screen (or scanning a printed copy) in order to OCR the text.
So far as converting graphs to text... I'm not sure what you mean.
If you have already got the data in a text format (e.g. as a CSV file), I'd suggest you just use OpenOffice to reload it as a spreadsheet, and then construct whatever graphs you want there.
http://www.openoffice.org/
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"Striking up conversations with strangers is an autistic person's version of extreme sports."
Kamran Nazeer