Had a T-Hawk as my first plane, nice plane, easy flyer. I like you moved over from Cars, and actually learned to fly on my own, and have since joined a club and got my first IC model.

The battery's you're looking at are exactly the same size as the battery pack that comes with the T-Hawk, so they will be fine, and if you fly it so that you're climbing under power, and switch the engine off to glide round for a bit, you should be looking at flights of about 20 minutes each.

One thing you do need to remember, BE GENTLE ON THE STICKS!!!!!! Don't just pull full deflection to turn or climb like with a car, or you will smash it up in no time.