You need at least 17% +hit for your spells to not miss a Raid Boss. Misery from Shadow Priests and Improved Faerie Fire from Balance Druids give you +3% spell hit when you raid with them. This means you need at least 14% +hit when raiding (13% if you are a Draenei or will be in a group with a Draenei). So aim for at least 14% +hit.
Raid bosses have a 6.5% chance to dodge your attacks, which you need 26 expertise to negate. Because you should always be attacking the boss from behind, where it can not parry you, there is no need for more than 26 expertise.
As far as AP / Haste / Crit / ArP ...
Shaman often use what's called "Enhancement Points" or EP as a way to rate their gear. These EP values vary from Shaman to Shaman as your gear will differ. You can use programs like Rawr (
http://rawr.codeplex.com/) or EnhSim (
http://enhsim.codeplex.com/) to help you model your EP.
Once you have your EP established, you can use addons like Pawn (
http://www.wowinterface.com/download...7296-Pawn.html) to display the EP values in game.
A good read for any Enhancement Shaman, has lots of general information and discusses EP:
http://elitistjerks.com/f47/t20765-shaman_enhancement/
A discussion on "Best in Slot" (BiS) gear, highest dps rotation, which glyphs to use, etc:
http://elitistjerks.com/f79/t88300-e...on_3_3_onward/
edit: reviewing my response, I guess I did not exactly answer your question, "is there an addon that just tells me all of this?" I don't have a link to one, sorry!
The values you want to reach are the same for almost all classes, though.
All casters want at least 17% +hit. Now again, there's buffs and talents that give you +hit, so the exact amount will vary by class. Example: Shadow Priests have a +3% hit talent and a +3% hit debuff (Misery), this means that they only need 17 - 3 -3 = 11 +hit.
All melee dps don't want more than 26 expertise, etc.