Like every government everywhere, the Korean government has a long and storied tradition of getting things exactly wrong, of creating policies by fiat and without consultation that worsen the problem they were intended to address, and result in unintended consequences down the line. The newest proposed change to regulations for the single largest group of foreign temporary residents -- holders of 1-year E2 English teacher visas -- neatly fits the bill.
Here's a braindump of some tips and tricks for getting a job in Korea, and keeping it once you're here. I'll add to it periodically as I think of more. If you have any specific do or don't questions, or you disagree with any of my advice, feel free to leave a comment. Don't forget to check out my Teaching In Korea -- The Skinny as well, if you missed it the first time.
For the vast majority of people entering Korea to work as teachers, the E-2 is what they will be applying for. If you are offered a job, you can either apply for and get the E-2 before you leave your home country, or come to Korea without a visa and do The Visa Run later. The most common destinations for visa runs are Fukuoka and Osaka, in Japan. Both Korean embassies are well-used to the constant, endless stream of E-2 applicants trooping through, and are quite efficient. The do tend to have odd opening hours, but if you time things right, you can leave Korea one day and be back the next, E-2 in hand.