Soreness has nothing to do with it. Once you get used to working out at any level regardless of difficulty you won't be getting sore. Soreness is just from your muscles not being used to the workload. Regardless of how sore you are you are still damaging muscle fibers and you still need rest to repair and build muscle. Granted your workout sounds pretty light to me if you are only going to mostly failure on the last rep on the last set but you still need rest. Look at it this way. Weightlifting is what you do to tell your body to grow, rest and proper diet is what you do to allow your body to grow.

As for calories I have no information to go on. At the very least people here would need to know your height, weight, age, sex, and activity level. Better yet you could do a google search for BMR and there are a number of sites out there that list your BMR (how many calories you burn per day to sustain life) then you add in how many calories you burn daily based on your activities (there are also sites that list calories burned per certain activities). Then you look at your goals. Are you trying to add weight, lose weight, or maintain current weight?