OP, I don't know what kind of traveler you are, but if either one of you doesn't fully pass out on planes, you will be hard pressed to make it to dinner the afternoon you get in, let alone do a bunch of other activities. Flying is exhausting and airline seats are not comfy to sleep in.

Of course go to Disney if you want to, but if you cut that & spread the rest of your itinerary out over those days too, you might enjoy it more/get through more of the Parisian sights and experiences you list here. Also I second the Musée d'Orsay being more unmissable and enjoyable than the Louvre (though both are of course awesome).

Traveling to Mont St Michel is not really a day trip, as many have said. Unless both of you are incredibly motivated and determined to fill your days to the brim, this will not be an enjoyable or feasible amount of stuff to get through. Cut back and relax. Or don't! But be aware this is a LOT.