I'm fine with emperor if it's with standard settings (read: not technology trading off). The starting location will be a very big difficulty generator in itself.
I find aggressive to be more useful than protective in standard AW games. Not only does it help you on the attack, but easy access to the shock promo is very useful when defending. That said, I can play any leader--it doesn't have to be the "best" one.
Sounds good to me.Emperor/Normal/Continent/Random Leader & AIs ???
Some other thing just so you know, i think knowing how civ4 is programmed is a normal skill thing just as good players know about xml.