Re:Jtag pinning versus ICSP
Look at the PIC32 starter kits schematic.
As far as I remember, the on board PIC32 "tool CPU" uses JTAG for programming and debugging the "application" PIC32 ;=)
I mean, the PIC32 "tool CPU" (kind of "Pickit3" functionality) is connected to PC using USB device and connected to "application" PIC32 using JTAG.
This kit only operates in debugger mode even though the application CPU can execute code once the PIC32 "tool CPU" is disconnected from PC (and hence from MPLAB X).