Alonzo dapp execution costs

Hello can someone help me understand the execution model in Alonzo? I suppose that dapps will be executed on producer node which is slot leader and “billed” according to costs described in alonzo genesis? The reward for dapp execution will go to producer node that was leader and that made the block?

Or are they going to be executed everywhere? On all producer nodes simultaneously but only the leader producer will be awarded for execution? Or are they going to be executed literally everywhere? On every relay or node?

How is this going to work?