World of war craft help?

so I'm doing the free trial for WOW cataclysm and im wondering if i buy the regular version am i able to log back into my trial account permanently so i dont have to level back up again and so on?..... also i have reached level 20 in the 10 day trial account and i seems as though my quests no longer offer me exp but only gold. Is the game not letting me level up anymore? 20 points best answer