Mohandaseen and Dokki are fine to live in
Couldnt possibley say what average rent is, depends on what you want.
It's safe here, safer than some European citys
Good social life, but unless you go to an expat club it's difficult to go out on your own.
Westerners tend to be paid more than locals, but its not a great wage, friend of mine was a secretary at a school and was on 3000 LE a month, she had to supplement this by teaching english privately.
Average cost of living depends on how you want to live, I have a great expat package and I use it all!