Older leaves turning yellow on the stems of Euphorbia lambii is completely normal for this plant, and doesn't represent any sort of problem, it is just what the plant does to start looking more "tree-like" as it gets height. After 6 months of being in the ground, it probably doesn't need but once a month watering in the dry months, it is a pretty drought tolerant plant. If it doesn't bloom this spring, for sure it will bloom next year in winter/spring. The flowers on this are very similar to E. characias, except they don't extend as tall above the foliage, but they are the same chartreuse green in color. If you don't want Euphorbias to self sow around the garden, you'll need to cut off the seed heads before they dry out and pop seeds all over the area.

Specimen is in poor condition. Landmark examples with more typical lush dark foliage seen from highways and in public gardens in southern California and Hawaii. Sometimes sent up here and attempted outdoors, where it does not take very long to fail - not tolerant of very much frost, even a large old planting in California was nipped one year and although surviving showed visible damage later.

I don't see the variegation in the leaves, but the scalloped edges indeed look like Kalanchoe blossfeldiana. It looks nice and healthy!

If this were mine. I would turn into cuttings. It won't grow new leaves in the bare stem, Cut each stem about one inch below the last leaf. Let callus for a day. The stems are small so you shouldn't need any longer than a day or two for calluses to form over the fresh cuts. During those days keep in a dry shady spot on a paper towel. When a scab has formed over the cuts you can plant into a fast draining mix. I don't know what planting medium you're going to use, but it would be a good idea to add at least half pumice or perlite to mix. Even if the bagged soil says for succulents it usually has peat in it. Peat is no bueno for succulents long term. Peat can retain water or once dried out it can become very hydrophobic. So adding at least half perlite or pumice really helps with drainage, and stops the peat from becoming like concrete. When soil becomes like concrete it chokes the roots of your plants. Dont water the cuttings until roots form and no harsh sun. Just keep in an area with bright light not direct sun. With this plant you should get roots in about two weeks. Kalenchoes are usually fast when it comes to throwing out roots:). Once roots form you can begin to water and acclimating to more light. Goodluck:).