I will say you're wrong about following people through walls with radar hacks. The scaling is not exact with the radar and you can't know the exact position of a person behind the wall. Radar hacks allows you to see where your enemies are on the map, not through walls.

If you have questions about hacks just search for videos on google. "CS:S <typeofhack> hack" It will give you a good idea of how different hacks function from the hackers perspective.