In the film, how much is comedy and how much is romantic comedy? what were the humorous moments and why?

I'm going to assume that you are referring to the 1993 film version of the play. I remember the film being very playful and light. Sure there was conflict in it but Emma Thompson and Kenneth Branagh (king of Hollywood Shakespeare) lighten the mood with their clever banter. The comedy really is driven through these two actors who bring Beatrice and Benedick to life. I personally enjoyed the garden scene with all the eavesdropping and contrived set-ups.