Generally upto 3 months its 1 - 2 ounce every feed.. by 6 months its around 3 ounces.. It all depends on your baby's capacity and consumption.. If he cries for more then pls give.. 

Yes as per baby weight u should give if normal then u can the back cover of any formula milk u r giving.. Instructions and measurements mentioned there.

Pls chk with ur pediatrician. It depends on the  baby weight.