Methodology of simulation post-processing for metal parts in Abaqus

I mesh most of my parts in C3D8R. My simulation are quasi-static, and involve a lot of contacts. To model steel, I use a classic elastic-plastic behavior, coming from stress-strain curves we measured. I have the yield strength of the material and the strain at break. My questions concern post-processing.

If I want to estimate the risks of plasticity (Stress>yield strength), I usually analyze the Von Mises stresses at the nodes, and compare it to the yield strength. Is that correct? Should I use another value (Smax or whatever)? Should I model a coating of my hexa mesh with membrane elements to have more accurate stresses at the surface?

Now If I want to estimate the risks of break, I usually analyze the maximum logarithmic elongation LEmax, and compare it to the strain at break. Same questions : should I use the output E, PEEQ, ...? Is the post-processing on nodes of C3D8R correct?

Thank you for your help!