There will be so many photographic opportunities you won't believe it. I think the above has covered the culture of photography. From what I see in the TV dramas, Seoul is like any other big oriental city.
You might like to see the old palace, or MyongDong at night (bar district). Southgate may have been restored by now, but if not, it will be a burned out hulk. Even is restored, you would best photograph it driving by. East market used to be good for shopping and photography. Nam San mountain has a tower that used to be a rotating restaurant. You may or may not be able to photograph from it due to security concerns. The 63 Insurance building used to have an interesting view, but again, photography may not be permitted.
Don't be afraid of the food, but only drink bottled or boiled water. Even hole in the wall restaurants will have boiled rice water or barly tea. Some of them have the best food as well. Careful of the Soju. It is a potato based drink of some potentcy. Many Koreans drink it like water, but if you aren't used to it I would not. You might want to at least try Mokuli, a white, sometimes almost chalky rice wine. It isn't for everyone. Again, rice wines can slip up on you if you aren't used to them.
Do try some of the Korean foods. Bulgogi is a favorite of foreigners as well as locals. Other things foreigners can eat include yakimando, chapchaepap, and pokumpap (fried rice). But don't be afraid of other dishes. If you don't like them you can always walk away. That would include kimchi, but again, it isn't for everyone. It is made from chinese cabbage, red pepper paste, and garlic. It is sort of fermented, but not buried in the ground for hundreds of years as some popularly believe.
Enjoy. I haven't been there in about 20 years, so I don't really know the current Korea. It changed every time I left and came back. Talking to people and seeing the TV, it isn't quite the Korea I knew, but I would guess, still interesting. Most of the people will be pleasant, and some will probably try to practice English with you. Be patient.