I can tell you the details of your visit.
- You come here and are invited for a banquet.
- It turns out that there are still some minor issues who will stop you from signing the contract.
- These issues can be smoothed over with some gifts so they take you to a shop selling cigarettes and you spend at least 5000 euro on cigarettes.
- After that everybody is very happy and a contract is signed and you have a banquet.
- That will be the last you will ever hear of these guys and your contract is a useless piece of paper.

Just got soaked to the bones so can confirm the rain-season is not over yet

Looks like the rainy season started again ;-)

There is no way you can cross the DPRK-ROK border other than flying via Beijing.

The standard answer on questions like "where can I buy?" on this forum is : "on the internet".