4, I don't think telling him you're frustrated, or dictating how you feel things out to work, or any of this is needed.
STBX and I have a schedule. We stick to it. That's that.
If she asks me for an adjustment I say yes or no. If I say yes then I am not upset with her for asking. If I say no then she does what she needs to do. It works both ways.
If you decline an adjustment and he FAILS to keep the schedule then document that and get legal advice on what to do.
But take the emotion out of it. It's not for you to decide how it should work, what his priorities should be, etc. It's for you to be a good parent and flex when appropriate: occasionally, for the best interest of the children, when it doesn't negatively impact you, and when that flexibility is reciprocated for everyone's overall benefit.
If you don't have a set schedule or don't follow these practices it's on you to tighten in up. But please do eliminate all the emotion from any communication and stick to business. That means "I feel" statements as well as "you should". Facts. For the children.
Me:38 XW:38 T:11 years M:8 years Kids: S14, D11, D7 BD/Move out day: 6/17/14, D final Dec 15
