https://worldofwarcraft.com/en-gb/character/eu/aggramar/billyhater
https://worldofwarcraft.com/en-gb/character/eu/hellscream/billyhaters
I consider cloth classes among the easiest to gear (the only dungeon drop you need are the pants, all other socket gear you can get from quests, for accessories you can easily go with ilvl 28 MOP vendors - maybe just the rings you should get some heavy haste ones).
I agree with sp>haste>vers, but I would say the same for all 3 specs - mostly because mastery affects either only healing for healing specs (and you wanna do dps too) and only DPS for Spriest (that has extremely strong heals, bring mana pots and you get unexpected healing).
talents I like the death word one in pugs, not only for the reset that is very useful in pugs, but even because even if you don't kill your target outright - but he dies withing 7 secs - you still get the reset AND the 40 Insanity. Against rually (but they are not that heavy right now) or heavy premade is not as effective, but the others won't help you too much anyway, and beeing able to use the execute on a random dps and have it ready for the primary healer two seconds later is quite good for me.
PVP talent the Psyfiend, for the movement speed and 50% less healing received, on a 45sec I consider it a steal.
The health swap if you are with some other twinks, but I normally pug and I still like the little guy a lot.
For proffs you can go cheap and easy with 25 eng for frag belt and glider cloak, and tailoring 1 for nets.
BE you still need herb to justify the race somehow (give me back the darn silence) to get bloodthistle (drugs ahoy).
Mind your 2 big cds, the shadowfiend and dispersion - I screw them up most of the time, but they are really good.
As a final note, I would put it on a different level than other pure dps specs, like Hunter or lock, for the immense utility it brings with excellent off-heals, you can normally outheal leveler healers (I'm still looking for a mana generating gimmick, if some1 has some tips I would appreciate them very much)