I've been using my tufa pots for 4 years now and they don't show any signs of deterioration. I've heard they have a life span of about 10 years though.
There are lots of opinions about how long to cure the pots before planting in them - anywhere from a few days to 28 days. I personally cure them for 28 days in a waterbath. It "officially" takes concrete 28 days to cure well (but I guess it actually keeps curing just about forever) and I would just rather be on the safe side. But I know a lot of people only cure for a few days and seem to have good results, so I guess it's up to you. It's hard to wait 28 days - especially when you first get started!
No, that's not a semp in the last picture. I ordered a box of mixed succulent cuttings last Spring. Unfortunately none of them were named, just a box full. But they're not hardy in our zone so I just used them as annuals. That one is so pretty after it rains because rain collects right in the center. Then when the sun shines on it it looks like a diamond in the middle.
Congrats on your retirement - I'm so jealous!!! I'm sure you'll be so busy you won't know how you ever found time to work. Enjoy every minute!