CIS is clinically isolated syndrome. It is considered your first experience of MS but will not be labelled as MS until (and if) you have a second.
As clear as mud. In some cases they will see evidence of an earlier attack and you will remember unexplained symptoms for earlier in your life.
We all want a diagnosis to explain what is happening to us, but in a lot of cases it is not clear cut and observation over time is required.
Not sure if all neurological incidents have to be reported. My wife had a physical problem with one eye and after careful checking that did not need to be reported because the other worked.
DVLA are not too bad but it is another load of faff I expect you could do without. To a lot of us it feels like you are being kicked when you are down and the delays, particularly during COVID, are the last thing you want. But as a member of the public the last thing I want is people driving around who perhaps shouldn’t be.