http://www.1aauto.com/1A/-/Ford/Ranger
1A Auto shows you how to remove or replace the interior door panel trim on your vehicle. You need to remove the door panel for a number of different repairs, for example door handles, window regulators, power window motors, door locks and more. This video, will help you do this.
It depends on what exact truck you have. Some have a non-3rd party branded head unit, while other have a Pioneer branded one. I have 2 rangers, one with each of these configurations. They don't list the specs on them, but in any case it is less than 20 watts (RMS) per channel. If you install an aftermarket headunit with more than 20w rms (most are in the 18-25 range) you will see a noticeable difference even with the stock speakers.