Yes (I would suggest 8 gigs for dualboxing), Yes, Yes, Yes. Strategies are press buttons kill stuff get loot.
For first class I would suggest Dk, Druid, or Paladin. Dks start at 55 so you'll be able to farm a bit easier to make other classes go faster. They are also good levelers being able to DPS and tank well.
Druids and Paladins are good because they will let you try different styles. Druids can be Melee DPS (Cat), Ranged DPS(Boomkin), Healers (Tree), and Tanks (Bear). Paladins are the same minus having a caster form.