Hob install. Brass elbow joints or soldered copper joints

Yes there should be a stop valve at the gas hob. Regards, Carl.

As above plus compression joints are allowed in accessible places where they can be accessed to be tightened, eg underneath the hob behind the oven. Soldered joints are allowed everywhere and is the better choice where practical. Most if not all hobs need at least 1 compression joint to allow the hob to be disconnecred, reconnected. It would appear the hob is installed correctly as far as pipework is concerned Hobs can be awkward to install, often requiring a number of joints to route the pipework so it doesnt foul on the oven below it.

Gas pipe work should following the shortest and straight route and has minimum bends more bends and elbows you put on the pipe work it will reduce the gas pressure and you might need bigger pipe size, my advise is calculate your pipe size. About the gas valve for the cooker, as long as your gas meter and the gas valve is in a easy accessible place and has the handle, you don’t need to provide another separate gas vale( unles the gas meter is being shared between 2 flats)