He doesn't have to know them, he probably has enough management and lawyers on retainer to warn him about stuff like that. It's highly unlikely they haven't warned him about this.
Of course he does. But he tends to just do shit and let his lawyers figure it out later. Speculating from his past behavior, he almost certainly just fired everybody and his lawyers were like "yeah, you can't just do that, you have to do x, y, and z as well". At least this time, it seems that he's going to actually listen to his lawyers and pay out the garden leave.
Ehh, I assume he does when it comes to money. I might have a very low opinion of him but I'm holding out a tiny shred of good faith in him not being an actual lunatic. However unlikely that seems as time goes on.