I'm German. That's what we do...
Re:How does this combine with the original game?
You can use the tiles as an addition. They are numered (lettered) differently than the ones in the first game (going, if I remember right, from R to Y). They don't replace the original tiles.
Randomly built map should not be a problem. You can even use it with less than five players, the quests might be a bit longer because you have to check more tiles.
The task in the addition is to kill a dragon. Combine both games and you win be killing the Nameless OR the dragon. So you have an additional possibility, if someone seems to be far ahead in killing the nameless or gathering the magical ingredients for the weapon against the dragon.
While the mapboards can be stored in there original box I doubt this for the smaller chits (at least I put them all in on box).
Hope this helps.