OK, that's a very strange list of bugs. Never seen or heard of most of those before... I just need to clarify a few things: for all bugs apart from the DirectX, are you using Windows XP, or are you using Windows Me in all these cases?
For the DX problem: the most obvious things I can currently think of are making sure you have the latest drivers for your graphics card and the latest DirectX, and so on.
As for not being able to create a new unit, that does happen when the green population bar is full but not otherwise. You may be able to hack this by opening up "Options.exe" in your KKND2 directory and change the Max Units (and anything else you want to fiddle with).
If you pause the game and minimise it, and/or let your PC go into Standby or Hibernate, then the game can often crash out after a few minutes of resumed gameplay. This has happened to me. If that's the case, just quit KKND2 properly before doing these power actions.
As for 'mission failed' I will assume that you're playing a mission that doesn't involve keeping a certain unit alive... that would be too obvious. Perhaps you should try giving KKND2 a clean install, and failing that, re-installing Windows usually helps
Hope that helps, somewhat.
[ December 04, 2005: Message edited by: BoffinbraiN ]