Very few people who come here are actual teachers. The English you will be teaching is for the most part very simple. There will be the odd time when you forget things such as adjectives or pronouns, but for the most part you teach only conversational English.
My wife was very nervous about public speaking before we came here, but it hasnt been an issue for her, likely because students respect the teachers more than we are used to. Usually youre teaching elementary school kids with classes between five and fifteen students.
This depends on the school. I have taught in both situations and both have their advantages. Solo teaching is good because you have control of the class. On the other hand, I find teaching with a Korean partner easier because they generally plan the classes, and discipline the misbehaving students.
It is true that quite a few Korean teachers will use a stick as punishment for bad behavior, or failing to complete homework. Basically the students hold both hands open, and they receive a whack or two with the stick. Korean teachers usually understand foreigners wont use the stick and wont pressure you to use it. I do not suggest trying to convince them not to hit the students. Remember, you are living in their society, and this is how they do it.
This depends on the school, but I would say as a general rule you the amount of prep is minimal. There are also plenty of ESL websites available, with great teaching ideas, that just needs to be printed off.
I would say that 75% of the English teachers I know are under 30 years old, but I think people over 30 are realizing this is an excellent opportunity and are becoming more common. We have one teacher at our school who is 64, and loves it in Korea.
You will be asked to teach private lessons by people you meet in Korea. The pay can be tempting, but getting caught can get you fired and sent home.