More four-player Quoridor shenanigans
It’s another interesting problems that you submit here
For the First one, 
you're right, in this situation yellow must skip his turn, the rules with all the differents explanations implied that.

For the second case,
It’s quite easy when you refers to the rules and it’s not a tortured reading of the rules you just have to follow the legal move in the Fig 10 (fig who show the legal move in a case of a jump with two pawn in front of you )
Yellow can escape in jumping in the upper square of the red pawn.