pawsplay
Hero
Only if that's what the GM chooses to do.
Sure, sure. Obviously, any game system is subject to a lot of variation between campaigns.
I'm just starting an M&M campaign. I've told the players to make 135pp PCs at PL 9. I've further told them that I intend to advance the campaign to PL 10 fairly quickly, but then remain at PL 10 indefinitely. (Right now I have in mind to stay at PL until they have about 190 to 200pp, but that's subject to change, especially given that I'm a new M&M GM.)
Power Level is not "level," as you seem to want to insist it is. PL could just as easily have been called "Power Tier." SK probably should have used another name, if the confusion and misinformation in this thread is any indication.
I think your post demonstrates how M&M's PL system allows you to graduate characters to a higher level, hence Level makes sense to me. Tier means literally the same thing as level, anyway. A three-tier cake has three layers, or levels.