Thanks everyone for your input! There's lots of articles out there about cactus soil, and I went with what I thought would work. I'll be switching it up based on everyone's comments. If anyone is curious about the pot, I just use it as a regular planter with lots of gravel & perlite at the bottom for drainage. It seemed to work for the first cactus I put in there (whose still happy with his home!). Thanks again!

Sand is not your friend - make a potting mix of 1/2 sifted C&S-specific soil (to get out the barky chunks) and 1/2 pumice (preferred) or perlite (acceptable), and this is just one of many soil recipes you can be successful with, and your plants should respond favourably, but if you feel you must use it, it shouldn't comprise much more than 3% of your potting mix recipe. Having grown Kals all my succulent life, in both one of the best places (San Diego, CA) and one less so (Kamloops), I find that they grow similarly in both places, as they're very avid to grow when it's not too hot (less than 90F) and not too cold (more than 50F), on average. Of course the growing season is longer in SD, less so here in BC, but if they get light and warmth and some water, they're growing now, and throughout most of the year. As you may know, they're opportunistic, so if you can give them good growing conditions, you'll see growth on them much/most of the year.

There is still life there :) But possibly some dead and/or rotting stems. It was overwatered as you realized. Your soil looks dark (wet soil looks like that) and quite organic = it will keep wet for too long. If nothing else, get a bag of perlite, sift or rinse it and use it generously mixed with C&S soil. At least 50% of total volume (could be eve more) of perlite. Take plant out, get rid of old soil. Any damaged stems and roots (dry or rotted and broken) should be cut off with sharp knife/blade. Keep healthy leaves, they could grow into new plants. Let cuttings callus for a day or two and prepare new mix. Use pot with drainage holes. Many ppl prefer terracotta, but plastic is just fine. Pot callused cuttings into new mix. Do not water until roots start growing - that is when new growth starts to be visible. Keep out of strong sunlight for about a week or so, and start moving into stronger sunlight every few days. It should do well in good sunlight as long as it is acclimatized to it. Lay leaves on top of the mix. Some may start growing roots and plantlets. Treat them same as cutting (could be all in same pot). These plants (and many other succulents too) will grow air roots - np. Leave them, or cut off if they bother you.

As I said many times, I also keep all succulents in full sun - from sunrise until about 6pm or so. Yes, it is 'only' Ontario, Canada sun :) Few are on shelves that are attached to the back of house and get sun from sunrise until only 1pm. I do same as Dinie - if a plant looks like it is protesting, I just put a taller one in front of it. Some jades (Crassula ovata) are good for that, since they are taller and have bigger canopy...My Kalanchoe tomentosa seems to like full sun too, it bloomed first year I kept it in full sun, outdoors, from early spring on - it didn't bloom in following years.