I'm not an expert on drugs, but isn't cocaine supposed to be a really short high? You snort in the evening and it's not impacting you by the morning?
Sure, if he's doing it before or during a match it might impact his ability to referee. If he's doing it in the evening, that's more a focus for law-enforcement more than a sports issue.
And yes, I suppose if he's doing coke, he's probably doing other stuff too... Which might impact his ability, but no evidence of that yet.
Depends on how much you use. If you're only doing a few lines then you won't feel any impacts of it the following day whereas if you're doing a gram or two you most likely will. Especially if you sit up half the night on it.
Not too dissimilar to other drugs like alcohol I guess. If you have 2/3 pints the day after effects will be minimal whereas if you drink 6 plus half a bottle of spirits you're gonna feel pretty ropey.
In my experience the mental side of the comedown exacerbated by lack of sleep is much worse than the physical side.

