As for myself I can say that I'm currently using a 40/21/0 spec that is based on demonic sacrifice for max dot/seed dmg. I find this spec pretty nice since I usually dont have a need for 4 pets. It also gives me 5x instant fears that is very handy.

I leveled up with a demo-spec from 60+. I think that would be one of the best choices before you get seed, because 4 felguards gives you a lot of aoe dmg/tanking while you can both dot and hellfire ALOT of mobs.

As for BG, I have done all of them. When I'm solo, I usually do AV. Here my tactics is usually to defend Galvanger. 4x Seeds is just insanly fun here. I usually hide myself at Galvanger so noone really know how many/what classes that stand there. Using this tactics, I can potentially wipe 10+ people comming to kill him alone. After most give up on Galv, I usually go for either to clear bunkers(if few are attacking) or defending the base/graveyards(if there are enough hordes attacking) When I'm defending I can often hold them off long enough for my side to win the battle.

As for AB/WSG/EOTS I usually do this with my guild groups, as this BG's requires a lot more teamwork, and is hard to do with 3-4 people allways following you around to look. However if you have a good group, you can really do well here too.

I havent done any arena to speak of yet, but I plan to use my 4 locks in arena with a friend as a healer. I think healing too in arena would require too much attention to be any efficiant.

I have a lot of macros, a bit too much to post here, but if anyone want any tips for anything special, just ask away.