Regarding the coefficient part of "moment Coefficient"... you'll see tons of co-efficients in aerodynamics. This is cause engineers hate to have to use units when they talk to each other. Making something (like Lift, Moment, Drag, etc) into a coefficient means that you have divided it by something that has the same units. (i.e. To make lift, in lbs, into a coefficient, you divide it by "SOMETHING" that has the units of lbs.). This is called non-dimensionalizing. You can choose what you use to divide it by arbitrarily, but there are conventions for the standard coefficients. For instance, to get coefficient of lift from lift force, you divide the lift by dynamic pressure and wing area.

Often the coefficients are more useful to work with because the aircraft geometry, and flight condition are taken out of the picture. If an airfoil has a maximum Cl of 2.1, then that's it's maximum at any speed, or wing size. This way one set of wind tunnel data can apply to many different wings (assuming you match the Reynolds and Mach No. but that's another thread :P).

I hope I haven't confused you, but the main thing to remember is that when you see "coeffient of XXX", it means that they've somehow removed the units from XXX so that it can apply to more than one situation.

Regards,
Tom