Also commenting about airport security searches and simular. Isn't that also supposed to stop other crimes too? Or does it exist a special anti-terrorist unit on the "floor" so to say?

For intelligence services, sure, although most focus is supposed to be on radical groups more than race for best effect.

For the average cop, airport security etc it's not as effective.
It alienates the profiled group and gives a predictabillity pattern that can be abused.
Now I don't say that you have to search truly random, but being too systematic isn't good. If always search the arab dude, and never that small girl or elder lady, who do you think will be smuggling bombs/weapons/stuff after a while?