[RPG] the name of the default D&D 4E world containing the Nentir Vale

The Shadowfell and the Feywild are alternate planes that mirror the real world, rather than places in the real world.

There is a box set due out Summer 2011 called Threats to the Nentir Vale

So far there are a fair number of maps of vale on google images, but other than the slight expansion of of the area to the south, in P1 King of the Trollhaunt Warrens, I don't know of anything else official.

edit:

As noted in answers to Is there a world map for the core campaign setting for DnD 4e?, http://www.wizards.com/dnd/files/Nerath_Map_HighRes.jpg is a map of Nerath, in which the Nentir Vale is found

The canonical "true/current" version of everything is found in the compendium, here (subscription required to use as more than an index).

There are, at present, three current "Cleric" classes you can play. I define a cleric class as anything that counts as a cleric for purposes of feats, beyond that of multi-class.

There is the "original" Templar Cleric. Recently renamed from "Cleric", the templar cleric is the cleric of healer's lore, lasers, and optional pacifism. A number of its powers have been errataed to reflect appropriate range and power. (Otherwise it was a rather superior controller.) The most important errata is the limitation on buffs to surgeless healing, and is the only critical errata to apply. (Basically the rule of thumb is: if you don't pay a surge for it, it doesn't get buffed by anything)

There is the essentials Warpriest. The warpriest is a simplified melee cleric featured in the essentials books. It uses domains and features the current domains of death, earth, storm, and sun. Death is debuffy, Earth is forced movement, storm is buffing, and sun is glowy (that's a shocker right there...) I am not aware of any major errata that must be applied to the class to correct game-breaking brokeneness. The warpriest shares few mechanics with the Templar, and should be considered a different class that shares feats, general role, and PPs.

There is the PH3 Hybrid Cleric that stinks. Avoid it. But it's there. There are no major updates for the hybrid cleric.

Sources of truth

The most important source is DDI. The second most is the Rules Updates. Everything that appears in a book is compiled and/or changed in those two. DDI is more authoritative than the rules updates because sometimes wizards engages in "stealth nerfs" (see Divine Oracle) that aren't loudly announced and may or may not be reflected in the rules updates.