go on youre account page and choose character transfer ( not copy, its for test server). It lets you transfer youre toons from deactivated server to an active server.
As far as my understanding goes the 10 days are an extra bonus for resubbing its not a trial. You get just 10 days for free without any retrictions.So youre reactivating will get you 40 Days of time instead of the normal 30.
after my finger got tired of pressing F5 ..i followed the link you get in youre e-mail from Fileplanet, that youre open beta code is valid. it took me only 5 times F5 to get the download rolling