Certainly looks like it's in trouble. Agree with Rina. The thing is, leaving it out to "dry" may not be the total answer. As Rina said, if there's rot, the only thing to do is cut the stem back to healthy tissue, allow to callous for several days and plant in some type of gritty mix and water VERY sparingly, if at all until new roots appear on the stem. If all else fails, not to worry as this is a somewhat common Echeveria and it wouldn't be the first plant most of us have lost! If you can't locate more at a BBS, let me know as I'm certain we can work something out.

Very possible that the little black fellows are aphids. If so, they suck plant sap and will weaken the plant. Rub them off, or use direct hits of insecticidal soap, diluted according to label directions. In both cases, repeat as needed. I'm not able to see enough detail to suggest what the white might be.

Eta: I typed this out a little bit ago and forgot to submit so I hadn't seen the other responses when I did actually submit :) It's hard to say without photos. I'm wondering if dabbled shade was not enough light for it. How often were you watering? And when you did water was it a deep thorough watering? What kind of mix was it planted in? My black prince was my very first succulent, before I really understood their needs. I initially didn't water quite often enough and I definitely was not giving it enough light. Across the span of maybe 4 weeks, it changed from the dark purply color to bright green and then lighter green. The leaves started to droop downward and were floppy; the leaves also seemed further apart and it became slightly etiolated. With that said though, it definitely was no where near death and has made a comeback (makes me wonder if something else was going on with your plant like a pest or something). I put it in better soil (50% perlite/50% c&s mix) and provided much more light. Here are before and after photos. May 15 June 11: (Has gotten darker since then)

From what I can tell looking at photos, marks in photo #3 look like water marks - hard water leaves them on the leaves. Could be from store if you got them recently. When watering, wet the soil mix, not the plant. I use collected rain water - if you have access to outdoors and containers to collect (and want to do the 'work' :) Leaves could get misshapen for many reasons: most often - mechanical damage (plants squeezed together; something falling on them; critters nibbling and so on). Could be also just a bit of decay that has already healed over from leaf being torn or nibbled on. Plant will not die - just aesthetics. Birds sometimes pick on juicy leaves, but usually leave bigger 'poke' marks. Squirrels, chipmunks, mouse, voles - they will chew off bigger pieces (if they like the taste :) - see my Kalanchoe...must be tasty : Oedema could be just a raised 'pimple' or a spot. Here are both on a jade plant. It has been raining lately just about daily and my plants are outside - there will be, most likely, lots more oedema - I am away and can't put plants indors: If you try to get rid of pimple, you have to scratch hard and it will leave a raw wound that would scab over. Best is to leave it and eventually, leaves will be replaced naturally. There is some, possibly, on underside of your E. Perle von Nurnberg in photo 4. I can't tell you what the tiny circular mark/crater is in photo #1 from. But I wouldn't worry much about it. Good there is perlite and pumice in your mix - but if mine, I would add much more. Perlite (sifted or rinsed) would be enough, is it easier to get. IMO, better draining mix would have just about equal amount of perlite and/or pumice and soil. Something like this (photo from another member):