Shaun only has you do power knees on one side during the fit test. You only do the fit test 5 times so I didn't worry about being "lopsided". He has you do power knees in a few other workouts but he does balance those on both sides.
Push-up jacks were hard. Especially at first. I only did about 18 on my first test and my form was nothing to write home about. The low obliques were really hard my first time. My hips and calves muscles were actually cramping up on me that first and second time. They get easier.
Simply continue to modify and take notes on what you did to compare that with your next fit test. There is no way you can't improve if you continue with the workouts.
Do what you can on each workout and don't forget it's okay to modify. If you watch the workouts even the super fit people in the DVD need to take breaks. These workouts are about pushing yourself beyond your limits.
How was day 2? or are you on day 3?