These cards seem like they're in the wrong place...

Indeed. I've deleted the others, fixed up this as best as I could, and moved this one to CWNH.

Confusing. What exactly means to die to combat damage? I know what most people think, but that isn't very clear.

If it's dealt 4 combat damage, and then 3 from a Lightning Bolt, does it trigger? What if it's in the other order? Damage destroyed it, and damage marked it doesn't remember if it was from combat or not.

If it's dealt 4 combat damage, and then it gets Last Gasped? It's still destroyed by damage, and now the only damage there was from combat. But is it clear enough?

If it's given indestructible and dealt 7 combat damage, but then it loses indestructible, it's still destroyed by damage, and all of it was from combat. But that happened a lot of actions ago.

If it's dealt 7 combat damage by a source with wither or infect, people would think it died by combat damage, but there's no damage marked on it. It would be treated the same as if the counters were from anywhere else. It wouldn't even be destroyed, just put into a graveyard.

Finally, about this card in particular, why would you want regeneration if it already has that ability? (I would also argue the high toughness but that's more reasonable.)