Return of Reckoning

Which classes are in demand/needed on each faction? Are any of them new player friendly? Never played warhammer online but it looks very interesting. 24 classes is kind of overwhelming tho

Hi, welcome, and yes RoR is great.
If you come to Order: priority to Melee DPS (Slayer, White Lion, Wich Hunter) -> Tanks (Swordmaster, KotBS, Ironbreaker) -> Healers. Forget about range DPS, we just have too many of them.
Also grouping/finding a guild improves your fun and experience.

Have fun and see you on the battlefield.

Swizz

Most important for new players is to connect with others. Playing healer or tank makes it easier to find groups/warbands.

On a different note, spend some time to modify your UI with add-ons, their effect is game changing and as new player you need the improved information a custom UI gives you.

I'd have to disagree with @mryay. If you want an easy DPS, go Witch Hunter (organised groups won't like you as it's a solo class) or go some ranged DPS like Bright Wizard. For a tank I'd go KOTBS, it's very simple to play, just put the correct auras up and guard your target. Iron breaker and Sword Master are a lot more difficult to play properly. For healer I'd suggest Arch Mage or Rune Priest as they're further back from the main action. Warrior Priests are more tanky but to be an effective healer you need to be up close to the action, and if you mess up your positioning or skills you'll die fast.