If you think that you are at the right point in your career to get an MBA, then I don't think length of work experience should prohibit you from applying. I worked in the biotech field and had about 2Y work experience when I entered Fuqua. I feel that you just need to make an especially good case of why now is the right time for you.
Banking and finance experience is definitely not a requirement for application. Duke is strong in Marketing and your marketing background would serve you well.
There is one student coming from the State Development Bank of China. Long working experience should be your advantage. Several Chinese students have more than 7 years working experience of class 2006.
At my first school visit to Duke, I was once thinking that I was traveling in a forest. Actually, Duke is much beautiful than what the pics could express, and in Duhram, there are lots fun places to go if one has enough energy. I love the city and the community very much.