Pagoda can be researched on the Internet, via Google. Search under Pagoda teach Korea.
You might want to open yourself a "throw-away" email address and post it here for teachers in the know to write you privately about the schools they know.
Teaching adults is easier than teaching children, but you may have to teach on split shifts, early in the morning and then later in the evening.
For a newcomer to Korea, established chain schools may not offer the highest salaries but they are stable, they pay correctly, on time and are more likely to meet the terms of their employment agreements.
Having said that, I will add that, with some chains its a gamble, some schools are well managed and some are not. Reputable schools will draft a sensible contract with provisions for pension plans and medical insurance. Vacation and sick leave terms are clearly stated.
Long distant calls are expensive, but getting mixed up with an unscrupulous hakwon is far more costly. Arrange for a telephone conversation with the director of the school. If he/she cannot speak English, you will have a tough time working there unless you can speak Korean. If they are not willing to answer your questions you will know, from talking to them, that something is wrong. Ask to communicate with the outgoing teacher by phone or by email. If they refuse to let you contact their foreign teachers, forget about them.
Schools that for years, give the same old one or two foreign teacher email addresses are suspicious. Also schools that promise very high wages (2.9 million,3.5 million won...) to a newcomer are too good to be true.
There are a few good and established recruiters in Korea that have been operating for several years, but BEWARE! Some are unscrupulous commission chasers just passing through.
There are exceptions to this, but in my opinion, the best opportunities are in the larger cities, Seoul, Deagu and Busan.
The eslteachersboards Read-Me-First Link is chock full of valuable information and links.
Hope this is helpful. Good Luck.