Re: Working with, around or against canon.
Depends on the canon.
For instance, settings like the Warhammer 40k universe or Tolkien's Middle Earth are very friendly about allowing players to expand on the canon and still remain true to it. On the other hand, if you wanted to play a historical setting, adding to the canon might be less fun than going against it and taking your direction toward historical fiction.
I don't expect you to agree with what I say, but at least defend to the death my right to say it!