About Emax:
it represents the slope of the line connecting the telesistolic points of different LV pressure-volume loops. The steeper the slope , the higher Emax, the higher LV contractility (attached figure).
In a simplified model it can be approximated by the ratio between LV pressure and volume at telesistole in single loop.
Emax is most easily understood from the Suga-Sagawa model of cardiac contraction: The heart is considered as jumping between two conditions which both can be represented by a compliance: diastolic compliance and systolic compliance. An activation curve describes the time course of the change from diastolic to systolic compliance. A volume with large compliance that is filled with blood in the diastolic phase will develop pressure when the compliance is decreased when it goes to the minimal systolic compliance, in the course of which the aortic valve is opened and flow is delivered to the aorta. The inverse of compliance is stiffness or E - defined by the Young's modulus of the material, i.e. cardiac muscle in this case, relaxed (low E) or contracted.(max E).
The other issues are well answered on Wikipedia.
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