Apple has never designed and produced a phone that allows for the user to replace the battery.
Since you already know of ifixit, if you purchase a battery kit from them, they supply all the tools required to replace the battery.
The videos give you a good idea as how to replace the battery, but don't expect the adhesive strips to give up without a fight.
After installing a couple batteries in iPhone 5's, I mask at least half the length of the adhesive strip with scotch tape so that subsequent replacements are easier.
I looked at the iPad battery replacement videos, and I won't attempt replacement due to screen breakage.