If the yellow jersey calls for one, pee stops for the peleton are mandatory.
If a train breaks up the peleton at a level crossing, and you’re on the far side, you wait.
The final stage should have no impact on the overall classification. But this year it will as it’s a TT in Nice, not a stroll down the Champs, so it will!
If the yellow jersey falls or has a mechanical, the group they’re in, waits. (Mostly true for any competitor with a chance to win in that group)
In a breakaway, if you’re competing for points in one classification, you don’t contest points in the others if other members of the group are trying for those. So if you’re rocking the polkadot, you take it easy at the sprints.