It seems that a kettle can mean a cauldron so my ignorance is the only problem. I have never heard it used other than for boiling water or the very specific fish kettle for poaching fish. But since we call timpani kettle drums it must be so... still seems a bit eccentric though.. like something my uncle, bewildered by dementia, would do...(he tried to run his lawnmower on claret last summer..) but it is clearly correct. The German Kessel means cauldron and boiler as well as kettle... typical Brits only caring about tea..
As for the leaven, I am on a baking kick at the moment and made sourdough bread at the weekend which made me think of it - I used a packet but I will try from scratch next time. Apparently it isn't hard just takes a few days to get going. I had to edit because I realised I had put it in French not English. And beekeeping is just something I want to do somewhen..