I'm not sure that there have been any huge changes affecting shamans. As you mentioned, there was a change to the faction system, so you may need to do some more faction grinding in some places.
Divinity's a good guild for the kind of thing you described. There are others too, but I'm biased
[You must be logged in to view images. Log in or Register.]
You can check out the wiki for spell and item prices.
Various guilds certainly let people tag along to loot tears. I'm not sure I know well enough to give you a list, but here are some guilds that to my knowledge currently raid planes off the top of my head: The Mystical Order, Bregan D'Aerth, Forceful Entry, Taken, A-Team, Divinity, Europa. I'm sure there are others. Ask around in /tells and you should be able to coordinate something.