Noobie Shaman Questions

[Hrothgaar]

Hi all,

after looking thrugh the DoTs of us shamans and the DoTs of the druids and necros I recognized that both the druids and necros get DoTs which seems to negate some of the resistances of the enemies.
As I am only lvl 14 and just started playing last week I have no idea how "valuable" the ability to decrease resistances is.

Are the DoTs of these other classes much more reliable than the shaman DoTs?

As a second question, I understand that casters specialize in one shool of magic at some point, what would be the adviced shool for a shaman? I found different meanings all around but I personally think that the DD line of spells might not be worth focusing as they are (as of now) really not that great.

And, as last question, because I am so low level my buff spells (strength, agi, dex, etc.) really dont add much to a group member, are they worth casting?
For example my str. spell gives +10 Str which is useful for carrying more but I didnt recognize that I do more damage with this buff active.
If they are not worth casting as of now, at which level would it be advised to invest mana in these buffs for the group?