I am looking to start fresh and looking for insight to what classes and specs are in need for both raiding and PvP. I'd mostly like to DPS, but wouldn't mind to go healing.
Kinda looking at shaman, but not sure if the DPS spec is considered in raids or PvP.
Another option I got is warlock for pure DPS. Is there any need for warlock?
There are the following S-tier DPS classes in PVP: rogue, warlock and mage (probably). In PvE, rogues suck, warlocks are superior to mages. Also, most would agree that in PvP warlocks are stronger than mages, especially in the late seasons. At the very least, a warlock is significantly easier to play in PvP than a mage.
Your choice of warlock is absolutely the right one.
In terms of TBC PVE pure dps classes, there is never too much hunters and warlocks because they do the biggest dps in tbc therefore they are welcome to fill up every free dps spot.
Shaman is also a good option, totems and bloodlust/heroism give great utility to party and raid, not to mention resto shaman is the best TBC healer. But even if you go as dps, utility you provide as shaman is enough to motivate other to take yo for raids.
In terms of PVP, i dont play PVP so i cant tell you anuthing about that. Just create character in blackrock for PVP.