It is hard to show you in the forums directly because Kongregate remove tags. I’ll try using pastebin. When you save your map, it looks like this:
And you need to modify it so it looks like this:
After you’ve got your modified map, you go to the edit menu and click paste map and paste in your new map. Now the briefing is retained.
Scripting is a little bit more complicated. It is all based around NFAs (non-deterministic finite automata) which just means that you can have ‘states’ and ‘edges’ between them. Edges are tied to stuff happening in the game. And you can add actions to states which are run at the start. So the zombie hordes are actually controlled by scripting.