Looking for a few answers before I buy

I am seriously considering buying a 2007 Prius, and I just took one for a nice test-drive. However, I have a few questions. 1. The car I drove seemed to have trouble on a couple hills. Is this a problem others have experienced or could it have been because I was driving the car for the first time? 2. The second question is similar. When I was on the freeway, I had difficulty keeping the car travelling smoothly at one speed. Has anyone else had this problem or is it also an effect of my inexperience? 3. Finally, has anyone had any trouble with the equipment that regulates whether the car is using electricity or gas? If so, how many miles were on the car at the time? Was it still covered by the warranty? If no on the warranty, how much did the repairs cost? I appreciate any help you can give. Thanks.