Using Logic together with Yamaha CP88, stage piano

1. I want to route the audio from the CP88 via USB to the Mac computer where I have created an aggregate device of the CP88 + Motu 896HD. The aggregate device works fine but I can´t figure out how I route the audio from the CP88 to the Output channel of the aggregate device. I am using Logic as a DAW. The CP88-manual sais that you should be able to record audio via USB.

2. I also want to create an instrument in Logic that I can use to record my piano playing on the CP88. I want it to work like a "plug-in" which means that when I bounce a projekt I want the piano track to be included. The midi works fine but I don't here anything through my sound card (the aggregate device). I also want to be able hear the piano even when I am not recording. (monitoring of some sort?)

How do I do this, anyone?

Best

//Per