does someone know?
Also: can I save my nxt by copying the nxt folder onto an usb stick?
your nxt will be stored in blockchain.
you can store your pass-phrase on usb stick to save your nxt. (better would be in a password manager like keepass2)
the passphrase is the key to everything!
Ok. So I could erase the whole client folder and not safe anything exept the password and come back in half a year (if nxt still exists), download the new software and have my next again 8and receive and send them)?
That is different to other coins like bitcoin right where saving the folder of the client is a must?
That is wrong. To preserve bitcoins, you have to save the public and private key (and for the non nerds: save your wallet.dat). With NXT, you only save the private key (=your passphrase, which must be different to every other NXT password in the universe)