How many universes "branch off" from a "quantum event", and in how many of them is the cat dead vs alive, and what about non-50/50 scenarios, and please answer so that a physics dummy can maybe kind of understand?

(Is it just 1 with the live cat and 1 with the dead one?)

The answer is only true if the measured quantity has continuous spectrum, therefore not applying to the only explicitly mentioned example of the cat. Furthermore I don't follow your subsequent reasoning.

Taking the universe as a QM event most definitely implies there are uncountably many universes. The OP very clearly asked for non-standard instances of the question, and a generalization of the question most certainly applies thereto.

I certainly hope others do not continue to down-vote what they don't grasp, because LW will only be the worse off for it. (Not implying you down-voted, but if you weren't, then the one who did obviously hasn't the wherewithal to state an outright objection.)

Edit: if you don't "follow", at least state in what exactly you don't follow so that I can actually provide something to

your explicit satisfaction.