Is there some way to reduce the scroll sensivity on the map for choosing missions? As soon as my cursor touches the edge of the screen, the view flashes to the other edge. Rather annoying..

To answer your question: I have no idea. But I do know this was an issue with the original game and is not limited to this version.

I personally think it worked back in the day (with a real W95-W98). But after that, it started to be too high in WXP and later. Or maybe is just my memory tricking me :P

You can try out something like CPUKiller or CPU Speed Adjuster, so your CPU uses 99% so you can scroll normally in Dungeon Keeper map selection, no patches where made to fix this problem, except for Deeper Dungeons, where you can get this patch to fix the problem: Deeper Dungeons patchloader

As an alternative you can try out KeeperFX to play Dungeon Keeper on Windows.