Nice greyhound bitch
Over the next few weeks you will soon learn what is suitable for her, and how much you can trust her.
It could take six months before she is fully habilitated to your ways.
As regards ferrets, having her muzzled on lead, with the ferrets running around her, and give her a firm No! and tug on the lead, should work. Do this everyday, till the ferret can walk over her toes and she won't even glance.
If she is too mad for them, and this method doesn't work, then just keep her away from ferrets, or if totally necessary try something a little harsher, last resort