Well, having been involved with elementary school boys as both a teacher and a principal - I would want more information before I really began to worry.
Usually playful touching does not get reported by the child to his parents. So the first case is a bit unusual. Was this child a friend? When and where did it happen? Did the child feel like he was being picked on? Frankly, if I had been the principal - I would have had both kids in my office, found out what was going on, and the matter would have been settled at that point. Since I doubt that this happened in the classroom, not sure what a move to another class would have done. Kind of a whimpy move by the principal, but I don't have much info.
Licking across the face is kind of different. But, it was his friend. Bet he didn't tell his parents? The difficult thing about all of this is whose idea was all of this. Is there someone else giving your son ideas and maybe his impulse control is not so good? Point being - unless you know what is going on, its hard to decide who is at fault.
To enforce manners, actions at school, etc. Well, at home you can enforce things. At school, you cannot. To change behavior, you need immediate, short, consistent consequences over a period of about 3 weeks. That is why you trying to change something happening at school is very difficult to do since, there is no immediate reinforcement.
What you can do is to teach and reinforce at home behaviors which will carry over to school.
By the way, does he have an older brother?
Oh, and one other thing that I would feel bad about if I didn't mention it since I am also the CL here - http://www.medhelp.org/forums/ADD---ADHD/show/175
You said he is, "a distraction in class." Has this always been a problem or just this year. If it has always been a problem - have you looked into ADHD. Impulse control is a major problem at this age.
If you have any questions - please ask. Best wishes.