Question about pruning new fruit trees?

I am new to planitng and caring for fruit trees, but read up on how to plant them and water ect, and planted them inabout a month ago, i live in central indiana. I am needing advice however as differnt people have told me I need to keep alot of the branches trimmed off of the tree the first year others say i do not. so now i do not know to take some of the branches off or leave them. I planrted apple trees pear tree plum tree and two peach trees. I water them each week five gallon each and am also needing to know when i need to spray them as one peach tree is getting some of the leaves chewed on and the onluy thing i see on it is ants. Please adviser on proper trimming first year and acare of my trees. thank you.