Kristian - we all wish we could do that, but commonly available PCs are simply not powerful enough yet if you want lots of layers and effects.
The solution is to use hardware a bit more - a hardware mixer will allow you to have multiple PCs each sending out a full res, full frame rate feed that is then combined in the mixer. You just have to think carefyully about what you do on each PC.
DinkToys - you can have 2 effects overlaid by doing one as a clip effect and one as the global effect.
What do you mean by rotozoomer? The new resolume has a rotozoom effect available.
Dan.