I think this question is directed to me. You see, I upgraded from an EM0480 to a Compak K3 Touch just under a year ago ( and bought a VBM Domo Jr at the same time).
I love the Compak to death. It is just fantastic. I particularly like the stepless grinding as it enables you to make minute adjustments to the grind which, if you have a good espresso machine, can make a noticeable difference to the taste. I also particularly like the fact that it is doserless. This allows for precise dosing without waste.
But to answer your specific questions.
1] Forget the scale, it is only arbitrary. You will learn what your required grind will look like. Different beans, different humidity, different freshness all require slight adjustments. Another plus for stepless.
When not in use there is about a millimetre of play in the adjustment. This is taken up at time of grinding. Not an issue at all. Sometimes if I can see that the grind is not quite fine enough I lean on the adjustment ring to take up the one mil of slack which refines the grind just a tad. I have learnt to use this play to advantage.
NB Only adjust the grind while grinding with beans in the hopper.
2] I actually look for clumping. For me, when the grind starts to clump it is an indication that the fineness is close to correct. When you tap the portafilter on the bench prior to tamping the clumps dissipate anyway.
No static at all.
3] The tray catches 90% of any spill. Before buying the grinder I was worried about this also. In practice, any spill is collected with just one quick wipe. To me it is a non-issue.
4] Longevity? Dunno, it gives every indication of strength. Sounds great and I reckon Ive got it for a long time to come.