Probably do daily quests or heroic instances :)
These days, it is easiest just to do the quests in Icecrown to level pretty fast. You can go from level 77 to level 80 in just a few hours if you follow the quests.
Yes, a level 52 is able to get into Sunken Temple in World of Warcraft.
If you're new to the game, you should keep in mind that it takes longer and requires more experience to reach every next level as you progress.
Currently in Mists of Pandaria, the latest expansion to World of Warcraft, there are 90 levels.
One can purchase max level World of Warcraft accounts from a site that offers the services of selling World of Warcraft accounts. One example includes "BuyMMOAccounts".
25
A level 60 raid.
?? boss
wetlands
Level 14
Level 65 is required in order to obtain and use the gunblade on World of Warcraft. The gunblade is dropped by monsters whom are in the mid-65 level range.
Tanaris