The only way to really track calories burned is a heart rate monitor.
I don't use DP except to look stuff up that Fitday doesn't have....but I don't count calories burned when I decide how many calories I can have. It kind of negates to point of exercising if you eat the calories back.
As for sodium...unless you are eating a lot of processed stuff or have been told to wathc your soium intake I wouldn't freak over the numbers. I know I don't get as much as Fitday says because sometimes it looks like they add sodium for me...I hardly use salt when I cook. (Makes DH