What Ottos?
The Calvinist question is tricky. Since Hungary itself was more or less "safe" itself from the non-Catholic movements, the neighbours were indeed not. But the king/nobility/leadership were Catholic at all time i do not think, that would change.
Concurrent.. kinda yes. I expect to Hungary be remain an ally of the HRE and deny a new front to drain HRE power for France. Thats alone a huge set of butteflies IMHO.
That would require Louis to be much more intelligent than IOTL (although more intelligent Louis would likely try to avoid Mohacs in first place). After battle Louis should be angry at János Zápolya, who was (deliberately) late on battlefield and missed the fight.
Lajos got a lot of flak... IMHO undeservedly. He was in an impossible position already and while he indeed should have aimed to avoid Mohács as a place to take battle, he had to be some kind of superman to pull that out.
Szapolyai was again undeservedly targeted after the battle, it was not his fault that he missed the battle, he received confusing orders and when he was ordered to join the main army, it was already late.