Actually, serpent sting is a good one. It applies a dot to the target which will continue to do damage while you are using autoshot.
A good portion of a BM's damage is done by the pet so it is important to have the right abilities. Cower indeed is worth less.
Cats should have dash, claw, bite (for pve).
I don't train my pets any resistances untill I need it for end game raiding instances. And then I tame a pet specifically for that purposes, get the resistances and abandon the pet once I don't need that specific resistance any more. But untill then I use all the points I get into abilities and stamina and armor.
Also make sure that you use the pet's kill command (if available at your level).
I usually start out with marking before the pull, as soon as the tank has aggro I sent in the pet, apply the serpent sting, then arcane shot. If the mob is in position and I don't expect it to flee, I will apply concussive shot, cause it helps out the tank, if I expect the mob to flee at low health I make sure the ability is not on cooldown at that point, so I can stun the mob.
If you have it avaiable already use steady shot (I didn't look up exactly at which level which ability comes).
Other then your pet the bow/gun is really important. I'm usually lazy while leveling with keeping up with gear. The only item I really care about is the gun/bow, well and that I still have a lot of Agility, even if the items sometimes are up to 10 - 12 level below my own. That way I typically out dps even mages, only with good rogues I have a hard time (while leveling... at 70 raiding things change). Make sure that the weapon/s you use in main hand/offhand have lots of agility. Stamina is nice, too. High dps doesn't really matter that much for the melee weapons. You might want to consider getting a scope, too for the ranged weapon, at lower levels they are usually not that insanly expensive.
Wow Armory doesn't work at the moment for me either, so I can't look up specifics on your build and gear.
If you want to look up which abilities are avaialble to your pet at which level and how they can be achieved I suggest looking it up at petopia (http://petopia.brashendeavors.net/)
Good luck!
Ara