Hey, Guy! I've used about all the methods you mentioned to propagate Kalanchoe cuttings. LOL I really didn't see a lot of difference. But I will say -- please don't use any sand. It tends to compress around the roots and hold too much water. Just not worth the risk. I assume you are in SF Bay area (and not Tampa Bay - yeah, I'm a little snot sometimes) so you won't have to worry about excess moisture blowing in during the summer months. So a potting mix of 50/50 perlite and soil will probably work well for you. I get a lot of rain, so I tend to use an inorganic gritty mix of perlite, turface and granite grit. I can't get pumice here, but you can in CA and it is great. Since these mixes are dry, when I put my cuttings into it I don't wait more than a few hours for the stem to callus. Sometimes I will dip the stem into powder rooting hormone right away and pot it up a little later. As long as I don't water right away I don't worry about rot. After a week I may water a little if the cutting is starting to look dry, but if there are no roots the plant can't take up the water. Some people mist when the plant is dry. When you see new growth, start watering as usual. Here's my original plant with a couple of (etiolated) cuttings started - And like yours, I ended up with woody stems - So I did the cuttings and saved what I could. And they still bloomed! And eventually they grow up - and will probably be woody again soon! LOL Don't ask me why my plants are droopy - like a hanging plant! They always do that and I can't figure out why. I have them outside in partial sun. They fried in full sun for me. But they keep growing and blooming, so I'm happy!

I'm not sure if you mean 3/4 of a cm or 3 or 4 cm. They look bigger than 7.5 mm to me. Anyway, the one on the left might be a Plectranthus and the one on the right might be a Sedum but I'm not sure. Identifying plants can be tricky when they are small. A Sedum would probably want a better draining mix than you have. I'm not sure what soil mix you used already but it looks like it might be mostly peat. Usually we recommend cactus and succulent soil mixed with perlite at about a 1 to 1 ratio. Sometimes more perlite is used. The objective is to get a soil mix that won't stay wet for too long but how long it stays wet can depend a lot on where you live and if the plants are inside or outside. The Plectranthus, if it is the one I think it is, is a common house plant and tolerant of different soils and watering habits in my experience. Might be best to not keep both plants in the same pot. I'm not sure if your plants need more light or not. The Plectranthus is a scrambling plant. The Sedum looks like it might grow more compact if given more light. I don't recommend keeping them on a table in a room.

It’s really hard to tell because it’s been in too low of light and has become super etiolated. I’m trying to imagine what it would look like compact. I’m thinking maybe some type of Crassula. Are the leaves fuzzy?

It could be sedeveria, a cross between a sedum and an echeveria; there are many so, i could not begin to tell you which variety.