1.) a close friend
Due to the language used, like "dude" this definitely a close friend.
2.) a parent
This is definitely a parent, as the parent is impressed with either her kids' grades has improved or some other kid she knows.
3.) a neighbor
You are thanking your neighbor for shutting your gate since they made sure your dog didn't escape the backyard.
4.) a teacher
This is most likely you talking to your teacher, telling your teacher about your trip.
5.) a close friend
This is going to be your friend that you are speaking to, as you are talking in more of a excited tone.