Hey AussieDisneyMom. To answer your questions. The discount is 10%.
Coming from either LAX or one of the Regional Airports, you can catch small 6-9 person vans that cost nearly the same as the DLE busses, they are shared rides, so the drivers may/will pick up other passengers as you head into Anaheim. They take you directly to your hotel, but because it is a shared ride they may stop to drop passengers off on the way. We have never had more than 2 stops heading to our hotel.
In essence you get off the plane, text the driver, get your bags and walk out to the curb at the airport, there are stops at every major entrance to the terminals.
Depending on the size of your party, it can be a break-even cost or if you have 4 or more, it can cost you less for a private shuttle vs the shared shuttle.
Cost from LAX is $17 a person ( one way), and with a discount code the price is $15.30 ( I double checked and CANTR is still valid). I book using the shupershuttle app