The transducer needs to be raised up until the center seam on the left side is aligned with the bottom of the hull.
You also need to tip the back of the transducer down at least a 1/4″. Look at the transducer mounting instructions. If you mount it correctly it should work just fine at high speeds.
These changes should greatly reduce the rooster tail you are experiencing.
He is correct!
There is NO PLUG on a full out HDSI XDCR, only a cSI (compact) XDCR.
NO issue getting closer to motor as long as you have a bubble free water stream to have the XDCR in.