Stephen Camp had this to say on your first question, and snowman's observed data follows the same theme:
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As to your second question, while there are certainly differences in ballistics between common handgun rounds, the differences in effectiveness are not all that great, especially when you're talking about modern defensive ammunition. Honestly, though, what exactly constitutes 'handgun effectiveness' is a debate unto itself; obviously, it begins with hitting your target.
A search on '9mm vs. .45' could probably give you plenty to read, some factual, some dogmatic, and some just plain offensive. But remember, when comparing the diameter alone of any cartridge, the differences are really not that great. A 9mm bullet is .356" a .44 magnum is .429" and a .45 ACP is .452". (To get an idea of the extreme range of diameter between these rounds, hold your fingers .096" apart.) So, bullet weight and velocity play major roles here. In fact, bullet velocity has a bigger part in the KE equation, since it gets squared. That's why the 9mm moving faster may have a greater amount of energy than the .45.
Practical upshot in my mind? Shoot what you are accurate with, practice lots, and don't get caught up in caliber wars.