I've heard of the priority issue, Midnight. I've just never noticed a difference when I retrain pets.
Go download and install Omen, hybrand. That will help you manage your threat and keep yourself under your pet's aggro to mostly solve that problem. You'll likely find you can not just throw every sting and special shot at the target while avoiding pulling aggro. Send in your pet and give him a second or two to fight solo before you start helping him out.
For pet abilities, you want the maximum level of growl available plus the maximum 'focus dump' attack skill, like gore, claw or bite. Put those on autocast. If your pet can use gore, that's best. If the decision is between claw and bite, go for bite. You need not train more than one attack skill. However if you find your pet's focus bar is always full during fights, then you should train a second attack skill. A full focus bar means some of it is going to waste.
Edited, Aug 18th 2008 10:20am by ItsaGaAs