Media questions

I am abt to buy a Canon M400 camcorder.  It accepts 2 SDXCs  I am think class 6 should be fast enough for this HD movie camera.  AM I thinking correctly.? Also- are SDXCs smaller in physical size than SDHCs?

Physical size is the same. Make sure to check with the host manufacturer to be sure what class is needed. Some hd cameras require class 10.