Gear in the dungeon finder is a great way to be "set for life".
You will find as you progress as a healer you will be able to get a large amount of virtually un-beatable gear. As you can (hopefully) see from the above I have gear that is 1 to 2 levels above me for my head, neck, off hand (including a shield) a cloak and after this was taken I got new legs.
Dungeon finder is gear easy for a healer, and as a shaman you can take 3/4 healing mediums. Cloth, leather and Mail are all yours, face it how many Elemental shamans do you come across? Only real issue is that you cannot need cloth and leather (at least I haven't been able to). This makes it harder to get drops unless you trade which you can do as long as the person who wins didn't roll Disenchant.
I'm over geared in relative terms for most instances I currently am running. I'm pushing the 1k spell power bracket, over 12k mana unbuffed (hope that is right now I've said it) and have started to enchant my gear with the left over cash I get from selling greens I pick up and boss loot.
As a shaman healer if you get dual spec like I have its not a hard choice to go elemental. You have the gear already, its basically the same requirement and you can do some PVP or DPS runs if you want a change of pace.
Enchants; Useful, expensive (at times) at not necessary at lower levels. While I can't talk as I have them its more of an accessory to my gear, none of its necessary as it will be replaced in a few levels, but if you can afford it, why not. A buff is a buff, and its semi-permanent and your choice. Need for mana per 5 or intellect? you have spare cash? Enchant yourself even if it lasts only a few levels you still get the benefit.
Remember to always take your enchants and gems into account when trading out gear. No point dropping an enchanted item to go backwards (unless you enchant the new one, your better off with the old). This does two things, 1 you hold onto gear longer and 2 you sell new gear quicker, especially when you start to double or triple up on items.
Anyway over gearing is good (but can ruin the fun when the content is to easy). Have fun, level up, and READ THESE ARTICLES !
Egamad of Caelestraz
(Foo's note: Your making my lack of posts look bad - keep up the good work)