It copies just about everything, however for AoE effects it will only copy one hit instead of every individual attack, which was changed sometime in Wrath or Cata if I recall correctly. Prior to that, every attack was duplicated, meaning if your Whirlwind hit four targets, you'd get 8 attacks out of it. Hilariously awesome as it is, it's also just a little overpowered!
I didn't cover anything too in depth because this was a simple "what changed in 6.0" guide, not a full blown "I've never played Arms before" guide. With regards to Sweeping Strikes, nothing changed so I didn't feel the need to mention; for the same reason I didn't cover how to effectively use offensive or defensive CDs or use non standard talents like Mass Spell Reflection or Intervene in specific situations.
The actual Warlords guide for level 100 should be more in depth. If people need it broken down barney style before then, I hear Rossi is writing.