OK, in the game definition block you can define types, actions and properties - just like a normal object...
Now I can see why properties, and even types, could be useful to define and use here... But what about actions?
Do these actions behave exactly like normal custom "commands"?

Also, do these actions/properties get forced onto the objects throughout the rest of the game (I guess not - but I might as well ask while I'm here).

If anyone can answer these, that'd be nice as I'm just beginning a little demo thingy to show off various features of quest.

I doubt they act like commands, but I'm not sure what to think on the applying to all game objects. I doubt it works in the manner you think, and defining types in the game definition block probably refers to inherited actions of types.