No Maria, you've got to cut back more until you have good green viable stem. And as Jeff (CactusMcHarris) has said you don't need anything on the cut end. I leave cutting in warm indirect light sometimes for weeks and they just root from the natural humidity in the air. Having said this, it might not happen in very low humidity areas, but here in Michigan we almost always have 40% ~ 50% RH. I just cut this from one of my Echeveria to demonstrate what you want to see after cutting. I would allow my cutting to callous for at least a week until I see the cut end dry and looking like a callous on your hand or foot; it will look hard and dry and somewhat rough. The mix is something I make but you don't have to have the same thing. Again, as Jeff has said, Perlite is readily available at any Big Box store or Garden Center. Do NOT use regular sand because it packs down too much and dries slowly. If you have a problem finding something course or gritty, go to a pet store/Walmart/Target and ask for bird gravel; the stuff used on the bottom of a bird's cage that they eat to help digest food. It will be a bit pricey but if all you need is a small quantity, it will work. I'm personally not a fan of "Topsoil" as a portion of my mix because it won't dry quickly for me.

Those plants look too healthy to have rot! I had some babys rot through once, when I had too much water pooling on the surface. I added perlite to the soil and it seemed to fix the problem.

Just ignore the leaves for a bit:). Don't babysit them;). Until I got my own little CC and actually felt one. I can see why yours looked the way it did. Mine would have looked the same being in a box for 2 weeks, and who knows how that box was treated. Out of all my succulents my CC feels the most delicate. If I put it out in the sun I know it would just melt like chocolate. I have single Conophytums with barely any roots that feel tougher than my CC. My Glottiphyllum pygmaeum I can handle with rougher hands, and the leaves on those get messed up with one fingernail stab. I think once mine gains size it will get sturdier, but these guys are not your average eachie:). I'm guessing that's why we don't find them for $5 at Home Depot;). I can see why people have issues with them 100%. When they're small that's where the problems occur. Once they get nicely rooted and big you can exhale. A little;). I've just been lucky mine hasn't croaked yet.

This is long post, so I apologise in advance :) After cutting top parts off, you could leave all lower trunks with roots potted, and they may grow. It likely depends on how healthy plant is. Here are some 'leftover' stems after tops were decapitated, and they are growing new plantlets and/or branches - they are all different plants:Another possibility is that they may grow from the roots, right at the soil level; here are couple of examples - hope you can see them as they are quite tiny:Top parts that were cut off - cuttings, would be best to let callus = heal just for few hours, unpotted. After that, stick them into well draining mix and let grow. These should be kept out of strong sunlight until they start growing, and then slowly - every few days - moved into best light you have. 8cm pot isn't too small, I would put 2 - 4 cuttings in it, depending on size. You may want to consider another approach: try to get existing plants to be healthier. They may be quite weak from being in very low light. Let them grow for a while, but in better light - I would use those great windows you seem to have. After they get much sturdier, you could behead them as suggested. Cuttings that don't have any roots shouldn't be watered until they start growing roots. You'll be able to tell when you very lightly tug the cutting and feel some resistance - that means roots already started growing into potting mix. Or when new growth starts appearing. Leftover stems with roots can be watered regularly. I would improve the mix for potting them. If nothing else, get a bag of coarse perlite and mix it 50:50 with soil. I would not follow advice you were given - ..." only water with a syringe, only a few drops will do"... Succulents need to be watered thoroughly when all the potting mix in the pot is almost completely dry. That could be few days or longer. It all depends on the mix and the temperatures. That is why you need to improve drainage of the mix and use pots with drainage holes. Plastic pots are just fine (I have about 200 succulents in plastic pots), but if you prefer terracotta, use them. If you have water-retaining mix, plastic or terracotta pots will not make too much of difference. Your Kalanchoe tomentosa needs more light too. They will grow woody and longer stems as they get older. Rosettes should be quite tight and leaves will get rich color in good sun:Pls. ask any questions you may have :)