How much food & milk should my son be having in 24hrs?

As breastmilk or formula should be the bulk of his nutrition the entire first year, I would give him more formula and a little less food, especially starches, which seems to be the bulk of his solids now cereal, potato and spaghetti purees, and yogurt, which is usually sweetened). You can also allow him to do some of his own feeding and phase out the purees.