world of warcraft Dungeons

If a group of people enter an instanced dungeon, how does a new player join that group or enter their dungeon?
The group leader can add a new player to the group without actually being near that player. Once the new player is added, he or she can enter the same instance that the rest of the group is in.

Will there be advanced areas or dungeons for high-level players?
Yes. The game will feature a wide range of content suitable for all levels and types of players, allowing both casual and hardcore gamers to enjoy their gameplay experience.

Will there be maps in dungeons?
Yes, the mini-map will display your immediate surroundings and it will function just like it does anywhere else in the world.

Are there areas that must be unlocked by a key?
Yes, but if you have a Rogue in your party, it can use its lockpicking skill in case you find yourself without the proper key. There are also puzzles that require players to locate the proper key to open a dungeon.