I've read online that some over-the-counter drugs in the U.S. would require a prescription in Korea.
Do you have a resource that tells U.S. expats what is NOT available in Korea or anything that would require extra "work" or extra cost to get? (e.g. prescription drugs, certain foods, toiletries, electronics, etc...etc...)
Medicine in Korea is a little different. For the most part, when you go to a pharmacy (because that's where almost all medicine is sold), there will be very little medicine within reach. By that I mean that you will have to tell the pharmacist what's ailing you and they will make the selection for you. The medicine they give you will not be a bottle of cough medicine or a bottle of pills. Rather, it will be individual packets filled with powder (or something else). The amount is going to be enough only for you to complete your course. They will not give you more than you need.
There's not really an official resource since most over-the-counters in the US don't exist here. There's no need either. Koreans prefer their way and, in all honesty, I actually recover much quicker here than I did in the US.
As for the other part of the question, I think I should refer you to my "What to Pack" and "Western Food" posts. For available food check out EZShop Korea. Those links cover most of that in detail.
If anybody has any questions, just send me an email at firstname.lastname@example.org or leave a comment.