As someone who's solo leveled a hunter and geared him for heroics, i can tell you that theres a huge difference in dps as your ap goes up (duh right). I had 1600 or so when I first hit 70 and i could solo mobs quite well, even one shotting mobs in hellfire with aimed shot crits. At 2150 or so ap I tear mobs apart, and if I'm not careful can drag em off all but the best tanks also. Hunters are very gear dependent at 70 to get the most out of them. The right talent spec helps also, I'm marks with enough in survival for imp traps, and a few points in the bm tree for the ranged dps talents there.

As far as bringing in a healer, why not bring a shammy, the totems will help the hunters, and they can self rez. Also has elemental totems so heroics might be more viable, at least the easier ones. Also consider speccing at least one hunter for beast mastery, so one pet can attempt to tank better, and also use traps for cc, so imp traps is quite nice for this. Once you get steady shot, remove arcane shot from your bar, steady shot is better dps/mana ratio, and will allow you to pump out the dps longer. Do the nesingwary quest line in nagrand as soon as you can, and get the gun, even if you dislike guns because of the noise. You won't get better until 70, unless you get one from shattered halls, shadow labs or steamvaults. At 70 do av until you get the season 2 xbow, and get faction with cenarion up to get better arrows. You'll want the cenarion rep anyways for the shoulder enchant.

Hunters the easiest class in the game to play, but playing one well takes skill just like all other classes. Gear helps alot, and having the right spec for your playstyle does also. For pve marks is generally best in my experience, pvp bm for the added survivability of you and your pet, and survival adds alot of utility to complement the other 2 specs.