Choice of bypass capacitors for PIC18F4455
I'd look at demo and evaluation boards for the processor or something similar to it. The first one I found had 0.1uF on all of regular VDD pins. There was a 6.8uF on the VDDCORE.

http://ww1.microchip.com/downloads/en/DeviceDoc/PIC18%20Starter%20Kit%20User%20Guide.pdf

If you are having problems with EMI though, you will have to tune those capacitors to your operating frequency and PCB layout.