I left the front panel connected and it was much quicker. But, if you have to wrestle with the battery, it is much safer with the front panel removed. If you have worked on a few phone before, I'd try removing the battery with the front panel connected. If the battery is giving you problems(like if you tear the strips and have to heat the backside), you can always come back to this step.
Before you start on the battery, jump ahead to step 27. Click the "this guide" and read and watch the video. Then come back and start on the battery. The adhesive strips are difficult the first time. They work like 3M Command Strips products, if you've ever used those. Stretching them lengthwise makes them release.