Hello Ghin,
im not familiar with K-visa I came on IR-1 spouse visa and no documents were handed over it was only the passport and the visa stamped on it with instructions to pay the green card fees online. Nevertheless, I took with me all the papers I used to submit my visa in an envelope but they never asked to see any paper.
it should be similar for you, if they gave you envelop then it should be it and take all your documents with you in case they ask to see any papers … when you get your passport with visa they usually stick to it a paper with instructions if there is anything to be done.