Hi

Keyclone is fine as a key replicator if you just want to level toons but if you want to get serious then ISBoxer is a stronger choice. HKN is also a free alternative but needs scripting.

As for classes, you want to macro as much as possible, therefore proc-heavy classes are not ideal (saying that, I'm currently boxing enh shaman and fury warrior so it can be done, albeit poorly). I suggest you play with what you like as all classes are viable (and pretty much the same anyway). The only thing to bear in mind is if you want ranged DPS or Melee (melee can be more difficult due to facing mobs issues).