Text in cells breaks to the next line automatically. Opportunities for linebreaks are blanks, hyphens and soft hyphens. If you have long "words" without blanks or hyphens, insert soft hyphens where you would allow linebreaks.
No linebreaks when you test with text like "Qweqweqweqweqweqweqweqweqweqweqweqweqweqwe". Use realistic text like "Qweqwe qwe qweqwe qwe qweqweqwe qwe qwe qweqwe qwe qweqweqwe qwe qweqweqwe" or "Lorem ipsum ..." for testing.
There is no "Auto" for column widths. You must specify the width for every column.
You can set the page to Landscape to have more space for columns.
If the PDF is primarily for on-screen usage, you can even increase the page width to make room for more columns.
That's what we do in some applications.
Samples with tables:
http://pdfsharp.net/wiki/Invoice-sample.ashxhttp://pdfsharp.net/wiki/HelloMigraDoc-sample.ashx