I typically have kimchi jjgae, it is fantastic! My favorite dish there.

There is no buffet.

If you order at least a day ahead of the time you can get them

Yes they do

I have never ordered jajangmyeon. However, I believe the owner is likely to make it if more than one person orders it. It's an authentic, delicious Korean food you will find there. We drive 1 1/2 hours to eat there.