Maintenance is being performed on all free servers right now, we're suspending and terminating accounts and services are being restarted periodically for this to continue, which may explain why you can't connect. Please disable multiple connections in your FTP client too, otherwise you'll get a temporary IP ban. It seems as though FTP is down on Cossacks currently, look at the service status link in my sig.
You can give FTP accounts to other people, yes. I wouldn't share one though, you may get suspended for it.
EDIT: FTP is back online, you should be good to go now.
-Luke.