Workout DVD

Okay I ordered the T25 and the Power 90. My plan was to start with the Power90 and after completing that moving on to the T25. However, only my T25 came and my Power 90 apparently won't arrive until Tuesday for some reason. I had my mind made up to start Monday morning. I also wanted to start with the Power90 because that program requires either weights or bands and I prefer to have a mix of cardio and lifting. Anyway, my questions now are:

1. would it make since to begin with the T25 since that is what I have and do the Power 90 after, or would the Power 90 no be a challenge after completing T25?

2. I need to lose about 20 pounds. Which program would give me the fastest results with clean eating?