The 5700BHS has AppRadioOne- which takes away the need for the proprietary Pioneer cables and the Apple adapter when using the AppRadio interface.
http://www.pioneerelectronics.com/PUSA/Car/AppRadioOne
You aren't seeing any apps in AppRadio with your iPhone because Pioneer has disabled them all. The keyboard used in apps with iOS 8 is not supported by AppRadio which has older keyboard libraries. Pioneer is refusing to update their libraries and, instead, is making all the 3rd party app developers change the keyboard themselves...