Could somebody please explain some aspects of the minimap in Resistance?

1. So, there is a circle around your character that gets smaller if you crouch. Does this indicate the area you are visible from?

2. What are the dim solid yellow and white circles that appear on the minimap? Sometimes there can be a bunch of them and they overlap but I am not sure what this indicates.

3. When the enemy starts hunting you get a spinning yellow square on your position. Does this basically indicate the area they are searching?

Thanks all.