If I call bitcoin client, it not ask for password. If anybody copy my wallet.dat, he can thefts my all money?
I may uninstall bitcoin client and remove all *.dat files except wallet.dat and no lose money?
That's right. If someone copies your wallet.dat they can spend your coins. If you lose it then you can't spend them, no other file matters. It's all public info that you can get again.
