Door panels are super easy to take off, but, if you don;t want to, choose a reliable shop.
http://www.msprotege.com/forum/showpost.php?p=4507252&postcount=8
Speaker power rating is the amount they can handle. Nothing else. Especially with a factory head unit, you always want to get the speakers with the highest Sensitivity, to maximize the low power of the amp.
In this case, getting speakers that handle more is a waste, unless you plan to add more amplification later.