Burro's tail definitely needs some help...looks like it is thirsty. They seem to like just a touch more water than majority of succulents. The 'crappy' soil doesn't help either, it is probably hard as a rock. Repotting it is a chore, since this plants leaves fall off at any time, as someone said- just by looking at it :)

But the plant doesn't look so good now anyway, so just bite the bullet and do it. You'll probably loose many more leaves, but in long run it will be much better off. Save the fallen leaves and throw them on top of mix after re-potting. Many will grow new plants and soon they will fill bare spots. Long stalks without leaves could be pruned off. Stick them into new mix, and they will grow too.

Don't be afraid to cut them off, plant will loose some length but bare stems are not attractive anyway, and you'll end up with much healthier and full plant.

These were such cuttings:

and here they are today:

I don't know anything about your other plant, someone will sure post...Rina