If I commit defiance but do not guess, I can put it under Diana ?

Send a rules query; the most we'll be able to do is give you educated guesses, as there's no concrete rules defining whether the standing effect counts as cancellation or not if it does not trigger.

No; if you don't draw the token you guess, you're not ignoring or canceling anything. Level 0 Defiance is almost useless unless you happen to pull a symbol with Premonition; the upgraded version can be comboed with Olive McBride or Augury, if you want to more reliably get it under Diana.