You'll likely find that the Wolves will work just fine for now. I'd recommend that you turn off "Growl" on one to allow more available focus on the other pet for damage output, and leave 'growl turned on for the other pet for tanking. For world trash leveling, this should work fine. In Outland, you'll likely need a real tanking pet, such as a bear or boar, although you might be surprised how well your wolves can do.

As SOON as possible, get "Beastal Disipline" in the Beast Mastery talent tree. The extra focus regeneration makes a world of difference in both tankiing and damage output. I'd strongly recommend that you get that on both hunters before spending any talent points in any other tree. If memory serves, you can have both points taken at level 31. Later, when you have much higher level characters, I'd suggest the talent "Go for the Throat" in the Marksman tree. With both skills combines, your pets will use focus like crazy to hold and kill your targets. In my opinion, these skills make more difference than the type of pet you select.

If doing an instance with a tank, of course you'll want to turn growl off on both pets. If you're going to depend on your pets to tank elites in instances, you will for sure want tanking pets! Hunters are great at leveling, but if you plan on doing instances with just two toons, you'll need to outlevel or outgear them by a fair margin. Instances are a huge jump for world mobs. Good luck, and have fun!