Did he find out what Willis is talking about?

Yes, He used that same statement when the Judge sent Willis to jail.

little arnold was confused on every show

It will forever remain one of life’s great unsolved mysteries

Nope

I think, and this is a total guess made up on the spot, that Willis was a prophet, and was telling him about his troubled future, and it wasn't allowed to be made public so they just made it enigmatic with that phrase whatchu talkin' 'bout?

hes dead now