K Visa Canadian and American in Korea, want to get married

[kida]

I am a Canadian citizen and my fiance is an American citizen. We are both currently living and working overseas in Korea. We have been together for 3 years and would like to get married. We don't know the best way to go about doing this. I'm not sure if it's easier to get married in the States or in other country, but we are planning to go to the US to get married. Is it necessary for my fiance to fill out the K1 fiance forms while in the states? Or can they be mailed from overseas? We are planning to leave Korea in a couple of months. He is planning to go back to university to pursue a masters degree. I'm wondering if this would be a problem when assessing his financial situation. He does not have any loans, nor do I. Thank you.