I am about to buy the AVH-X4500BT.  Does anyone know if the CD-IU201S or the CD-IU201V will work with the 4500BT?  Or do I have to get the CD-IV202AV to use the App Radio features?

here is the chart to see what cable you need for which features you want

http://www.pioneerelectronics.com/PUSA/2013+Pioneer+and+Apple+Compatibility

Is there any mods for this model? I've searched but can't find the model.

the AVH model line is nowhere near as moddable as some of the AVIC series are. I do not believe that Ive really ever seen any other than a hardware bypass if that even counts.