program/debug via the built-in usb in efm32
how program/debug silabs EFM32 via the USB built-in interface


Program: Yes, you can do that over USB with a bootloader. See AN0042.

Debug: No, for debugging you would need an SWD debugger, like the one on the DK or STK. I recommend using one of the STKs as there is plenty example code available for these and they have the debugger included.