Gittin 53: Intentional and Unintentional Offences; Damages that Cannot Be Seen

Again, my very limited understanding of property law makes it very difficult to comprehend the different levels of meaning in today's daf.  The basics:

• we learned a Mishna yesterday that one who causes a monetary loss by:
• rendering another's food impure
• mixing teruma with another's non-sacred produce
• pouring another's wine as a libation in front of an idol

          is not liable to pay damages if these things were done unintentionally
          is liable to pay damages if these things were done intentionally

Some considerations:

• how are these cases similar and different?
  
  
  are some of these circumstances uncommon and thus not punished?
• does the action actually cause damage to one's property?
• does Torah law rule that one pays the fine whether it is unintentional or intentional?
• is the unintentional action/actor not penalized to ensure that he informs the other of the damage done?
• Rabbi Yochanan: Torah law says that both actors are exempt from paying the fine for damages because there has been no damage; this will help people resist the urge to create impurities in each other's property when there is a dispute
• are the rituals of priests who do damage unintentionally relevant to this discussion?
• if the damage is not evident, should we say that the damage was unintentional?would these leniencies be mipnei tikun haolam, for the betterment of the world?
• The Gemara shares cases of damages that have and have not been evident and then categorized intentional/unintentional transgressions

It is interesting to note that the rabbis are so interested in intention.  We learn that in most cases, intention is not nearly as important as is action.  We can measure action, but intention is difficult to prove.  In these cases, the rabbis are eager to debate where to draw the line regarding intention and punishment.  Why?