Daniel's right. Basically, if you are looking at a set and asking the questions that Adam is asking, it probably means that your set could use more editing (though it could mean that your sense of what teams know about that subject is off). That's not the end of the world--sets always need more editing. However, tossups should be about topics that many teams know a few clues about and have more than one clue that most (though probably not all) teams know, and first lines of tossups should have clues that are less well known than the early middle clues where powers are often placed.
As to Coach Prince's question, I would tend to say that it's a bad idea. The reason it's generally not done is that, even though tossups should contain some consistency based on what I just said, there is always some inconsistency. It's difficult enough to make them all the same length, which beyond a certain range is more trouble than it's worth, and it's even more difficult to make them so consistent that at exactly three lines through you are at a particular difficulty level.
One of the things you want to do with powers is put them just before important words. To see how Prince's system might not work well, here's one of my questions from Solo:
The smallest cone on this mountain is Shira, and its bottom slope contains the town of Moshi. This also contains
features named Furtwängler and Rebmann. Two of this mountain’s three volcanic cones are extinct, while the Reusch
Crater on Kibo (KEE-bo) is dormant. The highest point on this mountain, which used to be called Kaiser Wilhelm
peak, is now called Uhuru (oo-HOO-roo) Peak. Located about 120 miles east of Olduvai Gorge, identify this
Tanzanian (tan-zuh-NEE-un) mountain which is the highest on the continent of Africa.
ANSWER: Mount Kilimanjaro
If the power mark was placed at the end of the third line, it would be between Kaiser Wilhelm and peak. This would be bad if a student recognized that clue, because whether or not they got the power could very well depend on buzzer speed, moderator reading speed, and moderator judgment. It would be better to move the power mark back a few words so it was just before the word Uhuru so that a student who recognized the Wilhelm clue would have a definite chance to get power.